CN110868589A

CN110868589A - Inter-frame prediction method and device and encoding/decoding method and device applied by same

Info

Publication number: CN110868589A
Application number: CN201810990347.3A
Authority: CN
Inventors: 杨海涛; 徐巍炜; 赵寅
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-08-28
Filing date: 2018-08-28
Publication date: 2020-03-06
Anticipated expiration: 2038-08-28
Also published as: CN117336483A; CN110868589B; CN117319650A

Abstract

The invention provides an inter-frame prediction method, which comprises the following steps: initializing a historical candidate motion information list corresponding to a current coding tree unit, wherein the historical candidate motion information list comprises N storage spaces, the initialized historical candidate motion information list comprises at least M vacant storage spaces, M is less than or equal to N, the current coding tree unit is contained in a coding tree unit set (Slice) formed by a plurality of coding tree units, and the current coding tree unit is not the first one in the coding tree unit set according to a preset processing sequence; adding the motion information at L positions in the spatial adjacent blocks of the current coding tree unit to the historical candidate motion information list according to a preset sequence, wherein M is less than or equal to L and less than or equal to N; inter-predicting the current coding tree unit or the current coding unit based on the historical candidate motion information list.

Description

Inter-frame prediction method and device and encoding/decoding method and device applied by same

Technical Field

The present disclosure relates to the field of video coding, and more particularly, to an inter-frame prediction method in a video encoding/decoding process.

Background

Video encoding (video encoding and decoding) is widely used in digital video applications such as broadcast digital television, video dissemination over the internet and mobile networks, real-time session applications such as video chat and video conferencing, DVD and blu-ray discs, video content capture and editing systems, and security applications for camcorders.

With the development of the hybrid block-based video coding scheme in the h.261 standard in 1990, new video coding techniques and tools have been developed and form the basis of the evolution of the subsequent video coding standard. Video Coding standards include MPEG-1 Video, MPEG-2 Video, ITU-T H.262/MPEG-2, ITU-T H.263, ITU-T H.264/MPEG-4 part 10 Advanced Video Coding (AVC), ITU-T H.265/High Efficiency Video Coding (HEVC) …, and extensions to such standards, such as scalability and/or 3D (three-dimensional) extensions. As video authoring and sharing becomes more widespread, video traffic becomes the greatest burden on communication networks and data storage. One of the goals of most video coding standards is therefore to reduce the bit rate without degrading the subjective quality of the picture compared to previous standards. Even though the latest High Efficiency Video Coding (HEVC) can compress Video twice as much as AVC without reducing the subjective quality of pictures, there is still a need for a new technology to further compress Video relative to HEVC, and a new generation of vvc (scalable Video coding) technology is being formulated, aiming at further improving the compression ratio by about 50% compared with HEVC without reducing the subjective quality of pictures.

In the HEVC/h.265 video Coding standard or the VVC/h.266 video Coding standard being established, a frame of picture is divided into non-overlapping Coding Tree Units (CTUs), and the size of the CTUs may be set to 64 × 64 or 128 × 128. Taking a CTU of size 64 × 64 as an example, it contains 64 columns of pixels, each column containing 64 pixels, each pixel containing a luminance component or/and a chrominance component. One CTU is divided into one or more Coding Units (CUs). A CU contains basic coding information including prediction mode, transform coefficients, etc. The decoding end may perform decoding processing such as prediction, inverse quantization, inverse transformation, reconstruction, and filtering on the CU according to the coding information, and generate a reconstructed image corresponding to the CU. And one CU corresponds to a predicted image and a residual image, and the predicted image and the residual image are added to obtain a reconstructed image. The prediction image is generated by intra prediction or inter prediction, and the residual image is generated by inverse quantization and inverse transformation processing of the transformation coefficient.

Inter-frame prediction is a prediction technique based on motion compensation. In the interframe predictive coding, because the same objects in the adjacent frames of the image have certain time-domain correlation, each frame of the image sequence can be divided into a plurality of non-overlapping blocks, and the motion of all pixel points in the blocks is considered to be the same. The main processing procedure is to determine the motion information of the current block, obtain a reference image block from a reference frame of the current block according to the motion information, and generate a predicted image of the current block, where the current block refers to an image block undergoing encoding/decoding processing, and the current block may be a luminance block or a chrominance block in one encoding unit. The motion information includes inter prediction direction indicating which prediction direction the current block uses forward prediction, backward prediction, or bi-prediction, reference frame index (ref _ idx), Motion Vector (MV) indicating a displacement vector of a reference image block in the reference frame used for predicting the current block with respect to the current block, and so on, and thus one motion vector corresponds to one reference image block in one reference frame. Inter prediction of an image block can generate a predicted image using pixels in a reference frame by only one motion vector, which is called unidirectional prediction; a prediction image can also be generated by two motion vectors using a combination of pixels in two reference frames, called bi-prediction. That is, an image block may typically contain one or two motion vectors. For some multi-hypothesis inter prediction (multi-prediction) techniques, an image block may contain more than two motion vectors.

One MV is a two-dimensional vector containing a horizontal direction displacement component and a vertical direction displacement component; one MV corresponds to two frames, each having a Picture Order Count (POC) indicating the number of pictures in display order, so one MV also corresponds to one POC difference. The POC difference is linear with time interval. Scaling of motion vectors typically uses POC difference based scaling to convert a motion vector between one pair of pictures to a motion vector between another pair of pictures.

In encoding, video Coding standards such as h.265/HEVC, h.266/VVC and the like divide a frame of image into non-overlapping Coding Tree Units (CTUs), and one CTU is divided into one or more Coding Units (CUs). One CU contains coding information including prediction mode, transform coefficients, etc. And a decoding end: the CU is subjected to decoding processing such as prediction, inverse quantization, and inverse transformation in accordance with the coding information, and a reconstructed image corresponding to the CU is generated.

In the code stream, the motion information occupies a large amount of data. In order to reduce the required data amount, the motion information is usually transmitted by adopting a prediction mode, wherein the prediction mode is divided into an inter-frame prediction mode and an intra-frame prediction mode, the intra-frame prediction mode adopts a reference block in the same frame image as a prediction block, and the inter-frame prediction mode adopts a reference block in a different frame as a prediction block.

The following three inter prediction modes are commonly used:

1) advanced Motion Vector Prediction mode (AMVP): identifying inter prediction direction (forward, backward or bi-directional), reference frame index (reference index), motion vector predictor index (MVP index), and motion vector residual value (MVD) used by the current block in the code stream; the reference frame queue used is determined by the inter-frame prediction direction, the reference frame pointed by the current block MV is determined by the reference frame index, one MVP in the MVP list is indicated by the motion vector predictor index to be used as the predictor of the current block MV, and one MVP and one MVD are added to obtain one MV.

2) merge/skip mode: identifying a merge index (merge index) in the bitstream, selecting a merge candidate from a merge candidate list (merge candidate list) according to the merge index, wherein the motion information (including prediction direction, reference frame, motion vector) of the current block is determined by the merge candidate. The merge mode and the skip mode are mainly different in that the merge mode implies that the current block has residual error information, that is, a motion vector acquired from a motion candidate list is used as a motion vector predicted value of the current block, the motion vector of the current block is obtained by adding the predicted value of the motion vector and the residual error value of the motion vector, and the residual error of the motion vector is obtained by decoding a code stream; the skip mode implies that the current block has no residual information (or the residual is 0), that is, the motion vector obtained from the motion vector list is directly used as the motion vector of the current block for inter-frame prediction; the two modes derive motion information in the same way.

3) Affine transformation mode: and obtaining the motion vector of each sub-block in the current block by the motion vectors of the two or three control points through affine transformation.

In the AMVP mode and the merge/skip mode, a candidate list needs to be established at first, for AMVP, a candidate motion vector list (AMVP candidate list) needs to be established, a better motion vector is selected as the motion vector predicted value of the current block, and the index value of the motion vector is written into the code stream; for the Merge/skip mode, it is necessary to suggest a motion candidate list (Merge candidate list) to be created, and the motion information candidates in the current motion information candidate list include one-way or two-way reference information, reference frame index, and motion vector information corresponding to the reference direction. Fig. 6 shows the specific locations of spatial and temporal candidate blocks that need to be referenced in establishing the candidate motion vector list and the current candidate motion information list in AMVP and merge/skip modes, the left diagram of fig. 6 shows that the blocks at the bottom right and center of the current block have been determined to be best suited to provide a good Temporal Motion Vector Predictor (TMVP), and the right diagram of fig. 6 shows that two spatial MVP candidates a and B are derived from five spatial neighboring blocks. AMVP allows a maximum of two candidate motion vectors, i.e. a maximum of 2 for the AMVP candidate list, while merge/skip mode allows more candidate motion information, and the maximum allowed candidate motion information in HEVC is 5, i.e. the maximum of 5 for the current candidate motion information list.

In the development process of the latest video coding technology, namely, multi-purpose video coding (scalable video coding), it is proposed to use historical motion information to extend the above-mentioned AMVP and optional motion vector or candidate motion information in the Merge/skip mode. In the jfet-K0104 proposal, a method of adding history candidate motion information (history candidate) to a fusion motion information candidate list and a candidate motion vector prediction list is proposed, so that the number of merge/skip fusion motion information candidates and Inter MVP mode motion vector prediction candidates is increased, and the prediction efficiency is improved. The historical candidate motion information list is composed of historical candidate motion information, wherein the historical candidate motion information is motion information of a previous coding block. In the jfet-K0104 proposal, a method of using a history candidate motion information list (history candidate list) and a method of constructing a history candidate motion information list are introduced.

The fused motion information candidate list added to the historical candidate motion information is constructed in the following manner (using method of the historical candidate motion information list):

step 1: the spatial candidates and temporal candidates spatially adjacent to the current block are added to the fused motion information candidate list of the current block in the same way as in HEVC. As shown in fig. 6, the spatial candidates include a0, a1, B0, B1, and B2, and the temporal candidates include T0 and T1. In VTM, the temporal candidates also include candidates provided by Adaptive Temporal Motion Vector Prediction (ATMVP) techniques.

Step 2: the historical candidate motion information in the historical candidate motion information list is added to the fused motion information candidate list, and a preset number of historical candidate motion information is checked in order from the tail to the head of the historical candidate motion information list, as shown in fig. 7. And (2) starting from the historical candidate motion information at the tail part of the historical candidate motion information list, checking whether the historical candidate motion information is the same as the fused motion information candidate in the fused motion information candidate list obtained in the step (1), if the historical candidate motion information is different from the fused motion information candidate in the fused motion information candidate list, adding the fused motion information candidate in the fused motion information candidate list, and if the fused motion information is the same, checking the next historical candidate motion information in the historical candidate motion information list.

And step 3: other types of fused motion information candidates such as bi-predictive candidates (bi-predictive candidates) and zero motion vector candidates (zero motion vector candidates) are added.

In the proposal of jfet-K0104, a historical candidate motion information list is constructed by using motion information of a coded block in a current frame, and the historical candidate motion information list is accessed in a first-in first-out manner. The overall historical candidate motion information list in the encoding/decoding end is constructed and used in the following way:

step 1: the historical candidate motion information list is initialized and emptied at the beginning of SLICE (SLICE) decoding.

Step 2: and decoding the current CU, if the current CU or the current block is in a merge or inter prediction mode, generating a fused motion information candidate list or a candidate motion vector prediction list, and simultaneously adding historical candidate motion information in the historical candidate motion information list into the fused motion information candidate list or the candidate motion vector prediction list.

And step 3: after the current CU or the current block is decoded, the motion information of the current block is added to the history candidate motion information list as new history candidate motion information, and the history candidate motion information list is updated, as shown in fig. 8. First, the motion information of the current block is compared with the historical candidate motion information in the historical candidate motion information list, starting from the head of the historical candidate motion information list. If a certain historical candidate motion information (e.g., MV2 in fig. 3) is the same as the motion information of the current block, this historical candidate motion information MV2 is removed. Then, the size of the historical candidate motion information list is checked, and if the size of the list exceeds a preset size, the historical candidate motion information at the head in the list is removed. And finally, adding the motion information of the current block to the tail part of the historical candidate motion information list.

However, in the process of constructing the above historical candidate motion information list, initializing the historical candidate motion information list when each slice starts encoding and decoding adopted in the prior art is not beneficial to the parallel encoding and decoding at the row level and the CTU level. In addition, the method updates the historical candidate motion information list table in each coding block, and the construction and updating time is long when the historical candidate motion information list is long.

Disclosure of Invention

In view of the above, the present invention provides an inter-frame prediction method and apparatus, and a coding and decoding method and a coding and decoding apparatus using the same. In a first aspect of the present invention, a method of inter-prediction is provided, which includes: initializing a historical candidate motion information list corresponding to a current coding tree unit, wherein the historical candidate motion information list comprises N storage spaces, the N storage spaces are used for storing historical candidate motion information, the initialized historical candidate motion information list comprises at least M vacant storage spaces, M is less than or equal to N, M and N are integers, the current coding tree unit is contained in a coding tree unit set (Slice) formed by a plurality of coding tree units, and the current coding tree unit is not the first one in a preset processing sequence in the coding tree unit set; adding the motion information at L positions in the spatial adjacent blocks of the current coding tree unit to the historical candidate motion information list according to a preset sequence, wherein M is more than or equal to L and is less than or equal to N, and the L positions in the spatial adjacent blocks are obtained according to a preset rule; constructing a current candidate motion information list of the current coding tree unit or a current candidate motion information list of the current coding unit, wherein the coding unit is obtained by dividing the coding tree unit; and inter-predicting the current coding tree unit or the current coding unit according to the combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or the combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit.

In the method, in the process of coding the current coding tree unit, the historical candidate motion information list is initialized, namely, an independent historical candidate motion information list corresponding to the current coding tree unit is constructed, so that the dependency relationship caused by constructing the historical candidate motion information list in the coding process of the coding tree unit is cut off, the coding tree unit can carry out independent coding according to the historical candidate motion information list, the coding efficiency is high, the coding and decoding parallelism of a row level and a CTU level is more favorably designed, and the coding and decoding time can be greatly reduced under the condition of ensuring that the coding quality is not lost basically through parallel processing.

In an optional implementation manner in combination with the first aspect of the present invention, the initializing the historical candidate motion information list corresponding to the current coding tree unit includes clearing the historical candidate motion information list such that M is equal to N. This way, the current coding tree unit can construct a completely new historical candidate motion information list to increase the accuracy of inter-frame prediction.

In another optional implementation manner that is combined with the first aspect of the present invention or is based on the optional implementation manner of the first aspect, M predetermined locations in an adjacent block in the airspace are used as source locations of the M historical candidate motion information, specifically, the M locations in the adjacent block in the airspace are locations where a first candidate motion information is obtained from a preset location in the adjacent block in the airspace, a location where the first candidate motion information is obtained is used as a starting point, and the remaining M-1 candidate motion information is obtained at intervals of a preset step size. In order to be unified with the existing historical candidate motion information list construction mode and have a simplified algorithm in the process of constructing the historical candidate motion information list, the motion vectors at the M positions are usually obtained sequentially from a starting point position at preset intervals, where the preset intervals may also be referred to as step sizes, and the step sizes may be fixed, for example, using 4 or 8 pixels as a unit; furthermore, the step size may also be varied, for example, different step sizes are set according to the size of the current coding tree unit.

In another optional implementation manner that is combined with the first aspect of the present invention or is based on any optional implementation manner of the first aspect, the adding order of the M-position motion information may be a preset order, for example, in a clockwise order, with a spatial neighboring block at a lower left corner of the current coding tree unit as a starting point, and with a spatial neighboring block at an upper right corner of the current coding tree unit as an end point, the motion information at L positions in the spatial neighboring block is added to the historical candidate motion information list. The acquisition mode aims at well matching the processing sequence of the spatial domain adjacent blocks and simplifying the read-write logic of the historical motion information, so that various different modes can be adopted. For example, in a counter-clockwise manner, or from spatially adjacent blocks at two endpoints, in opposite directions simultaneously.

In another optional implementation manner combined with the first aspect of the present invention or any optional implementation manner based on the first aspect, before inter-predicting the current coding tree unit or the current coding unit, the method may further combine a combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or combine the current candidate motion information list and the historical candidate motion information list of the current coding unit, which may specifically be: and adding the historical candidate motion information into a current candidate motion information list of the current coding tree unit or a current candidate motion information list of a previous coding unit, and then performing the inter-frame prediction based on the current candidate motion information list of the current coding tree unit or the current candidate motion information list of the previous coding unit. The processing mode can simplify the index operation of the motion information of the current motion coding tree unit or the coding unit, and after the motion information in the historical candidate motion information list is added into the current candidate motion information list of the current motion coding tree unit or the coding unit, the original candidate motion information and the historical candidate motion information adopt a uniform index sequence and index number, and an additional current candidate motion information list index does not need to be established, so that the index process can be effectively simplified.

In another optional implementation manner that is combined with the first aspect of the present invention or is based on any optional implementation manner of the first aspect, if a current coding tree unit needs to be further divided into coding units for coding, in addition to performing inter prediction on the current coding unit according to the obtained motion information, the method may further include updating the historical candidate motion information list based on the motion information of the current coding unit. The method can continuously obtain and update the historical candidate motion information list corresponding to the current coding tree unit so as to improve the accuracy of inter-frame prediction.

In another optional implementation manner combined with the first aspect of the present invention or based on any optional implementation manner of the first aspect, the above updating of the historical candidate motion information list may be divided into two cases, that is, if the M positions are not filled, the current coding unit motion information is added as historical motion information into an empty storage space closest to an N-M position among the M positions in the historical candidate motion information list; or; if the M positions are filled, removing the historical motion information which is added into the historical candidate motion information list at the earliest time according to a first-in first-out principle, shifting the position of the residual historical motion information which exceeds the removed historical motion information, and adding the motion information of the current coding unit as the historical motion information into the tail part of the historical candidate motion information list, wherein one end of the historical candidate motion information list, which contains the latest added historical motion information, is the tail part of the historical candidate motion information list. The method provides flexibility in the application of the historical candidate motion information list, that is, the historical candidate motion information list can be used for inter prediction of the current block when the historical candidate motion information list is not completely filled, and under the condition that the historical candidate motion information list is filled, the motion information/motion vector of the current coding block can still be used for updating the historical candidate motion information list.

In another optional implementation manner combined with the first aspect of the present invention or based on any optional implementation manner of the first aspect, in a case that the historical candidate motion information list is full, the motion information/motion vector of the current coding block may still not update the historical candidate motion information list, that is, inter-frame prediction is performed on another coding unit based on the same method as the current coding unit, where the another coding unit is located after the current coding unit and belongs to the coding tree unit with the current coding unit according to a preset processing order, and the historical motion information list used for inter-frame prediction of the another coding unit includes the historical motion information in the historical motion information list used for inter-frame prediction of the current coding unit. Specifically, if the M positions are not filled, adding the current coding unit motion information as historical motion information into an empty storage space closest to an N-M position among the M positions in the historical candidate motion information list; and if the M positions are full, performing inter-frame prediction processing on the next coding unit based on the current candidate motion information list. This approach may allow for parallel processing of the coding blocks within the current coding tree unit,

in another optional implementation manner combined with the first aspect of the present invention or based on any optional implementation manner of the first aspect, if the historical candidate motion information list is not full after traversing the spatial neighboring image blocks, or if the current coding tree unit is located at the top of a frame of image, or if the current coding tree unit is located at the left of a frame of image, any one of the following methods may be referred to process the unfilled portion of the historical candidate motion information list. The first method is as follows: and no motion information of any other source is filled, and the motion information of the current coding unit acquired when the current coding unit in the current coding tree unit is coded and decoded is used as the historical candidate motion information to be added into the historical candidate motion information list. The second method comprises the following steps: and filling motion information of the coding block at the preset non-adjacent position of the airspace of the current coding tree unit. The preset non-adjacent position can be a fixed interval with the adjacent position, and can also be a preset template. The third method comprises the following steps: and filling the coding block time domain motion information from the preset position in the reference frame, the position corresponding to the current coding tree unit and the position corresponding to the coding block adjacent to the current coding tree unit. The preset positions in the corresponding positions of the current coding tree unit can be extracted at fixed intervals or in a specific rule or sequence. The predetermined position in the corresponding positions of the current coding tree unit adjacent to the coding blocks can be a specific rule and a specific sequence. The method is as follows: and filling the coded block time domain motion information of a preset position in the corresponding position of the current coded tree unit and the corresponding position of the coded block of the preset non-adjacent position of the previous coded tree unit in the reference frame. The preset positions in the corresponding positions of the current preceding coding tree unit may be extracted at fixed intervals, or may be extracted in a specific rule or order. The preset position in the corresponding position of the coding block with the preset non-adjacent position of the current coding tree unit can be extracted in a specific order by a specific rule. The fifth mode is as follows: and filling the historical candidate motion information in the historical candidate motion information list of the coding tree unit adjacent to the current coding tree unit. Any one of the above filling manners for the unfilled motion list of the historical candidate information can enrich the historical motion information candidates in the motion information list of the historical candidates, and can complement the current motion information list of the historical candidates under the condition of insufficient spatial neighboring blocks or insufficient MVs of the spatial neighboring blocks, thereby fully exerting the coding and decoding gains brought by the motion information list of the historical candidates.

A second aspect of the present invention provides a method of encoding using inter-prediction according to the first aspect of the present invention: inter-predicting a current coding tree unit or coding unit based on an inter-prediction method of a first aspect of the present invention to obtain an inter-predicted image; subtracting the obtained inter-prediction image from the original image of the current coding unit or the current coding unit to obtain a residual image; and coding the residual image and the motion information index to form a code stream. It is noted that, as a decoding method, in the inter-frame prediction process, motion information of the current coding tree unit or the current coding unit is required to be acquired from a combination of the historical candidate motion information list and the current candidate motion information list, and inter-frame prediction is performed on the current coding tree unit or the current coding unit according to the motion information of the current coding tree unit or the current coding unit to obtain an inter-frame prediction image, where the motion information may be specifically acquired by parsing a code stream, a motion information index corresponding to the current coding tree unit or the current coding unit, and motion information of the current coding tree unit or the current coding unit is acquired from the combination of the historical candidate motion information list and the current candidate motion information list.

A third aspect of the present invention provides a method of encoding using inter-prediction according to the first aspect of the present invention: inter-predicting a current coding tree unit or a coding unit to obtain an inter-predicted image based on the inter-prediction method of the first aspect of the invention, and subtracting the obtained inter-predicted image from an original image of the current coding tree unit or the current coding unit to obtain a residual image; and coding the residual image to form a code stream. Wherein, in the process of obtaining the inter-prediction image based on the inter-prediction method of the first aspect, the method further comprises: acquiring motion information of the current coding tree unit or the current coding unit and a motion information index of the motion information from a combination of the historical candidate motion information list and the current candidate motion information list; according to the motion information of the current coding tree unit or the current coding unit, performing inter-frame prediction on the current coding tree unit or the current coding unit to obtain an inter-frame prediction image; and encoding the motion index.

Compared with the prior art, the encoding/decoding method adopts the updating of the historical candidate motion information list at the encoding tree level, allows the encoding and decoding at the row level and the CTU level to be parallel, and can effectively reduce the encoding time.

The present invention also provides inter-matrix prediction devices, encoding devices, and encoding apparatuses according to the first, second, and third aspects of the present invention, and a decoding device and a decoding apparatus according to the third aspect of the present invention.

The present invention also provides an inter-array prediction apparatus, an encoding apparatus and an encoding apparatus corresponding to the first, second and third aspects of the present invention, which comprise a digital processor and a memory, wherein the memory stores an executable instruction set, and the digital processor reads the instruction set stored in the memory for implementing the method provided by the first, second or third aspect of the present invention.

Drawings

FIG. 1 is a block diagram of an example video encoding system for implementing an embodiment of the invention;

FIG. 2 is a block diagram of an example structure of a video encoder for implementing an embodiment of the invention;

FIG. 3 is a block diagram of an example structure of a video decoder for implementing an embodiment of the invention;

FIG. 4 is a block diagram showing a block diagram including the encoder 20 of FIG. 2 and the decoder 30 of FIG. 3

FIG. 5 is a block diagram showing another example of an encoding device or a decoding device;

FIG. 6 is a schematic diagram of the positions of spatial neighboring blocks and temporal neighboring blocks of a current block;

FIG. 7 is a schematic diagram of adding historical candidate motion information to a fused current candidate motion information list;

FIG. 8 is a diagram of a historical candidate motion information list construction;

FIG. 9 is the motion information of the left and upper spatial domain neighboring image blocks of the front tree unit;

fig. 10 shows the flow of acquiring two spatial candidate motion information a and B.

FIG. 11 is a flowchart of example operations of a video encoder implementing the inter prediction method of the present invention, according to one embodiment;

FIG. 12 is a flow chart of a method for a video decoder to decode based on the inter-matrix prediction method of FIG. 11 according to another embodiment;

FIG. 13 is a flowchart of a method for a video decoder to encode based on the inter-matrix prediction method of FIG. 11, according to another embodiment;

FIG. 14 is a schematic diagram of an inter-prediction device provided with an implementation of the method of FIG. 11 according to another embodiment;

FIG. 15 is a schematic diagram of an inter-prediction device provided with an implementation of the method of FIG. 12, according to another embodiment;

FIG. 16 is a schematic diagram of an inter-prediction device provided with an implementation of the method of FIG. 13 according to another embodiment;

FIG. 17 is a schematic diagram of an apparatus for implementing any of the methods of FIGS. 11-13, according to another embodiment.

In the following, identical reference signs refer to identical or at least functionally equivalent features, if no specific remarks are made with respect to the identical reference signs.

Detailed Description

Hereinafter, specific embodiments of the present invention and application examples using the specific embodiments of the present invention will be described with reference to the accompanying drawings.

It is to be understood that embodiments of the invention are not limited to the examples set forth herein, which may be used in other respects, and may include structural or logical changes not shown in the drawings.

For example, it should be understood that what is encompassed herein by inter-prediction methods may equally apply to the corresponding apparatus or system for performing the methods, and vice versa. For example, when one or more particular method steps are described, the corresponding apparatus may comprise one or more units, such as functional units, to perform the described one or more method steps (e.g., a unit performs one or more steps, or multiple units, each of which performs one or more of the multiple steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a particular apparatus is described based on one or more units, such as functional units, the corresponding method may comprise one step to perform the functionality of the one or more units (e.g., one step performs the functionality of the one or more units, or multiple steps, each of which performs the functionality of one or more of the plurality of units), even if such one or more steps are not explicitly described or illustrated in the figures. Further, it is to be understood that features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless explicitly stated otherwise.

Video coding generally refers to processing a sequence of pictures that form a video or video sequence. In the field of video coding, the terms "picture", "frame" or "image" may be used as synonyms. Video encoding as used in this application (or this disclosure) refers to video encoding or video decoding. Video encoding is performed on the source side, typically including processing (e.g., by compressing) the original video picture to reduce the amount of data required to represent the video picture (and thus more efficiently store and/or transmit). Video decoding is performed at the destination side, typically involving inverse processing with respect to the encoder, to reconstruct the video pictures. Embodiments refer to video pictures (or collectively pictures, as will be explained below) "encoding" should be understood to refer to "encoding" or "decoding" of a video sequence. The combination of the encoding part and the decoding part is also called codec (encoding and decoding).

In the case of lossless video coding, the original video picture can be reconstructed, i.e., the reconstructed video picture has the same quality as the original video picture (assuming no transmission loss or other data loss during storage or transmission). In the case of lossy video coding, the amount of data needed to represent the video picture is reduced by performing further compression, e.g., by quantization, while the decoder side cannot fully reconstruct the video picture, i.e., the quality of the reconstructed video picture is lower or worse than the quality of the original video picture.

Several video coding standards of h.261-h.265 belong to the "lossy hybrid video codec" (i.e., the combination of spatial and temporal prediction in the sample domain and 2D transform coding in the transform domain for applying quantization). Each picture of a video sequence is typically partitioned into non-overlapping sets of blocks, typically encoded at the block level. In other words, the encoder side typically processes, i.e., encodes, video at the block (video block) level, e.g., generates a prediction block by spatial (intra-picture) prediction and temporal (inter-picture) prediction, subtracts the prediction block from the current block (currently processed or block to be processed) to obtain a residual block, transforms the residual block and quantizes the residual block in the transform domain to reduce the amount of data to be transmitted (compressed), while the decoder side applies the inverse processing portion relative to the encoder to the encoded or compressed block to reconstruct the current block for representation. In addition, the encoder replicates the decoder processing loop such that the encoder and decoder generate the same prediction (e.g., intra-prediction and inter-prediction) and/or reconstruction for processing, i.e., encoding, subsequent blocks.

As used herein, the term "block" may be a portion of a picture or frame. For ease of description, embodiments of the present invention are described with reference to VVC or High-Efficiency Video Coding (HEVC) developed by Joint Video Coding team (JCT-VC) of the Video Coding Experts Group (VCEG) of the ITU-T Video Coding Experts Group and the Motion Picture Experts Group (MPEG) of the ISO/IEC moving Picture Experts Group. Those of ordinary skill in the art understand that embodiments of the present invention are not limited to HEVC or VVC. May refer to CU, PU, and TU. In HEVC, the CTU is split into CUs by using a quadtree structure represented as a coding tree. A decision is made at the CU level whether to encode a picture region using inter-picture (temporal) or intra-picture (spatial) prediction. Each CU may be further split into one, two, or four PUs according to the PU split type. The same prediction process is applied within one PU and the relevant information is transmitted to the decoder on a PU basis. After the residual block is obtained by applying a prediction process based on the PU split type, the CU may be partitioned into Transform Units (TUs) according to other quadtree structures similar to the coding tree used for the CU. In recent developments of video compression techniques, the coding blocks are partitioned using Quad-tree and binary tree (QTBT) partitions to partition frames. In the QTBT block structure, a CU may be square or rectangular in shape. In the VVC, a Coding Tree Unit (CTU) is first divided by a quadtree structure. The quadtree leaf nodes are further partitioned by a binary tree structure. The binary tree leaf nodes are called Coding Units (CUs), and the segments are used for prediction and transform processing without any other segmentation. This means that the block sizes of CU, PU and TU in the QTBT coding block structure are the same. Also, it has been proposed to use multiple partitions, such as ternary tree partitions, with QTBT block structures.

Embodiments of the encoder 20, decoder 30 and encoding system 10 are described below based on fig. 1-3 (before embodiments of the present invention are described in more detail based on fig. 6).

Fig. 1 is a conceptual or schematic block diagram of an exemplary encoding system 10, such as a video encoding system 10 that may utilize the techniques of the present application (this disclosure). Encoder 20 (e.g., video encoder 20) and decoder 30 (e.g., video decoder 30) of video encoding system 10 represent examples of devices that may be used to perform techniques for fusion candidate list construction, and codec based on the post-fusion selection list, in accordance with various examples described herein. As shown in fig. 1, encoding system 10 includes a source device 12 for providing encoded data 13, e.g., encoded pictures 13, to a destination device 14 that decodes encoded data 13, for example.

The source device 12 comprises an encoder 20 and may additionally, i.e. optionally, comprise a picture source 16, a pre-processing unit 18, e.g. a picture pre-processing unit 18, and a communication interface or unit 22.

The picture source 16 may include or may be any type of picture capture device for capturing real-world pictures, for example, and/or any type of picture or comment generation device (for screen content encoding, some text on the screen is also considered part of the picture or image to be encoded), for example, a computer graphics processor for generating computer animated pictures, or any type of device for obtaining and/or providing real-world pictures, computer animated pictures (e.g., screen content, Virtual Reality (VR) pictures), and/or any combination thereof (e.g., Augmented Reality (AR) pictures).

A (digital) picture is or can be seen as a two-dimensional array or matrix of sample points having intensity values. The sample points in the array may also be referred to as pixels (short for pixels) or pels (pels). The number of sample points in the array or picture in the horizontal and vertical directions (or axes) defines the size and/or resolution of the picture. To represent color, three color components are typically employed, i.e., a picture may be represented as or contain three sample arrays. In the RBG format or color space, a picture includes corresponding red, green, and blue sampling arrays. However, in video coding, each pixel is typically represented in a luminance/chrominance format or color space, e.g., YCbCr, comprising a luminance component (sometimes also indicated by L) indicated by Y and two chrominance components indicated by Cb and Cr. The luminance (luma) component Y represents the luminance or gray level intensity (e.g. both are the same in a gray scale picture), while the two chrominance (chroma) components Cb and Cr represent the chrominance or color information components. Accordingly, a picture in YCbCr format includes a luminance sample array of luminance sample values (Y), and two chrominance sample arrays of chrominance values (Cb and Cr). Pictures in RGB format may be converted or transformed into YCbCr format and vice versa, a process also known as color transformation or conversion. If the picture is black and white, the picture may include only an array of luminance samples.

Picture source 16 (e.g., video source 16) may be, for example, a camera for capturing pictures, a memory, such as a picture store, any type of (internal or external) interface that includes or stores previously captured or generated pictures, and/or obtains or receives pictures. The camera may be, for example, an integrated camera local or integrated in the source device, and the memory may be an integrated memory local or integrated in the source device, for example. The interface may be, for example, an external interface that receives pictures from an external video source, for example, an external picture capturing device such as a camera, an external memory, or an external picture generating device, for example, an external computer graphics processor, computer, or server. The interface may be any kind of interface according to any proprietary or standardized interface protocol, e.g. a wired or wireless interface, an optical interface. The interface for obtaining picture data 17 may be the same interface as communication interface 22 or part of communication interface 22.

Picture or picture data 17 (e.g., video data 16) may also be referred to as an original picture or original picture data 17, as distinguished from the pre-processing unit 18 and the processed picture or picture data performed by the pre-processing unit 18.

Pre-processing unit 18 is configured to receive (raw) picture data 17 and perform pre-processing on picture data 17 to obtain a pre-processed picture 19 or pre-processed picture data 19. For example, the pre-processing performed by pre-processing unit 18 may include trimming, color format conversion (e.g., from RGB to YCbCr), toning, or denoising. It is to be understood that the pre-processing unit 18 may be an optional component.

Encoder 20, e.g., video encoder 20, is for receiving pre-processed picture data 19 and providing encoded picture data 21 (details will be described further below, e.g., based on fig. 2 or fig. 4, 5). In one example, the encoder 20 may select the most suitable prediction mode for the current block (the current image block to be encoded) according to the rate-distortion cost evaluation, for example, using intra-prediction or using inter-prediction. When the encoder 20 selects the inter prediction mode, the encoder may perform a method for inter prediction of the current block, that is, the encoder 20 first initializes a historical candidate motion information list corresponding to a current coding tree unit, where the historical candidate motion information list includes N storage spaces for storing historical candidate motion information, the initialized historical candidate motion information list includes at least M empty storage spaces, M is less than or equal to N, M and N are integers, the current coding tree unit is included in a coding tree unit set (Slice) composed of a plurality of coding tree units, and the current coding tree unit is not a first one of the coding tree unit sets according to a predetermined processing order; then, adding the motion information at L positions in the spatial adjacent blocks of the current coding tree unit to the historical candidate motion information list according to a preset sequence, wherein M is more than or equal to L and is less than or equal to N, and the L positions in the spatial adjacent blocks are obtained according to a preset rule; constructing the current coding tree unit or a current candidate motion information list of the current coding unit, wherein the coding unit is obtained by dividing the coding tree unit; and finally, performing inter-frame prediction on the current coding tree unit or the current coding unit according to the combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or the current coding unit. Based on the above method, the encoder 20 may obtain more various motion information during the encoding process to predict the current block, and it is not necessary to wait for the previous coding tree unit to finish encoding before processing the next coding tree unit during the application process of the historical candidate motion information list, so that the capability of parallel processing of the coding tree units in inter-frame prediction can be improved, and the encoding efficiency can be improved.

Communication interface 22 of source device 12 may be used to receive encoded picture data 21 and transmit to other devices, e.g., destination device 14 or any other device for storage or direct reconstruction, or to process encoded picture data 21 prior to correspondingly storing encoded data 13 and/or transmitting encoded data 13 to other devices, e.g., destination device 14 or any other device for decoding or storage.

Destination device 14 includes a decoder 30 (e.g., a video decoder 30), and may additionally, that is, optionally, include a communication interface or unit 28, a post-processing unit 32, and a display device 34.

Communication interface 28 of destination device 14 is used, for example, to receive encoded picture data 21 or encoded data 13 directly from source device 12 or any other source, such as a storage device, such as an encoded picture data storage device.

Communication interface 22 and communication interface 28 may be used to transmit or receive encoded picture data 21 or encoded data 13 by way of a direct communication link between source device 12 and destination device 14, such as a direct wired or wireless connection, or by way of any type of network, such as a wired or wireless network or any combination thereof, or any type of private and public networks, or any combination thereof.

Communication interface 22 may, for example, be used to encapsulate encoded picture data 21 into a suitable format, such as a packet, for transmission over a communication link or communication network.

Communication interface 28, which forms a corresponding part of communication interface 22, may for example be used to decapsulate encoded data 13 to obtain encoded picture data 21.

Both communication interface 22 and communication interface 28 may be configured as a unidirectional communication interface, as indicated by the arrow from source device 12 to destination device 14 for encoded picture data 13 in fig. 1, or as a bidirectional communication interface, and may be used, for example, to send and receive messages to establish a connection, acknowledge and exchange any other information related to a communication link and/or a data transmission, for example, an encoded picture data transmission.

Decoder 30 is used to receive encoded picture data 21 and provide decoded picture data 31 or decoded picture 31 (details will be described further below, e.g., based on fig. 3 or fig. 5). In one example, the decoder 30 may be configured to decode the data encoded by the encoder, which may specifically be parsing the code stream to obtain a fusion candidate index; acquiring a corresponding fusion candidate from the fusion candidate list according to the fusion candidate index and taking the fusion candidate as the motion information of the current block; performing inter-frame prediction on the current block according to the motion information of the current block to obtain a predicted image of the current block; acquiring a residual error image of the current block; and adding the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block.

Post-processor 32 of destination device 14 is used to post-process decoded picture data 31 (also referred to as reconstructed picture data), e.g., decoded picture 131, to obtain post-processed picture data 33, e.g., post-processed picture 33. Post-processing performed by post-processing unit 32 may include, for example, color format conversion (e.g., from YCbCr to RGB), toning, cropping, or resampling, or any other processing for, for example, preparing decoded picture data 31 for display by display device 34.

Display device 34 of destination device 14 is used to receive post-processed picture data 33 to display a picture to, for example, a user or viewer. Display device 34 may be or may include any type of display for presenting the reconstructed picture, such as an integrated or external display or monitor. For example, the display may include a Liquid Crystal Display (LCD), an Organic Light Emitting Diode (OLED) display, a plasma display, a projector, a micro LED display, a liquid crystal on silicon (LCoS), a Digital Light Processor (DLP), or any other display of any kind.

Although fig. 1 shows the source device 12 and the destination device 14 as separate devices, device embodiments may also include the functionality of both the source device 12 and the destination device 14 or both, i.e., the source device 12 or corresponding functionality and the destination device 14 or corresponding functionality. In such embodiments, source device 12 or corresponding functionality and destination device 14 or corresponding functionality may be implemented using the same hardware and/or software, or using separate hardware and/or software, or any combination thereof.

It will be apparent to those skilled in the art from this description that the existence and (exact) division of the functionality of the different elements or source device 12 and/or destination device 14 shown in fig. 1 may vary depending on the actual device and application.

Encoder 20 (e.g., video encoder 20) and decoder 30 (e.g., video decoder 30) may each be implemented as any of a variety of suitable circuits, such as one or more microprocessors, Digital Signal Processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, or any combinations thereof. If the techniques are implemented in part in software, an apparatus may store instructions of the software in a suitable non-transitory computer-readable storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Any of the foregoing, including hardware, software, a combination of hardware and software, etc., may be considered one or more processors. Each of video encoder 20 and video decoder 30 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined encoder/decoder (codec) in a corresponding device.

Source device 12 may be referred to as a video encoding device or a video encoding apparatus. Destination device 14 may be referred to as a video decoding device or a video decoding apparatus. Source device 12 and destination device 14 may be examples of video encoding devices or video encoding apparatus.

Source device 12 and destination device 14 may comprise any of a variety of devices, including any type of handheld or stationary device, such as a notebook or laptop computer, a mobile phone, a smart phone, a tablet or tablet computer, a camcorder, a desktop computer, a set-top box, a television, a display device, a digital media player, a video game console, a video streaming device (e.g., a content service server or a content distribution server), a broadcast receiver device, a broadcast transmitter device, etc., and may not use or use any type of operating system.

In some cases, source device 12 and destination device 14 may be equipped for wireless communication. Thus, source device 12 and destination device 14 may be wireless communication devices.

In some cases, the video encoding system 10 shown in fig. 1 is merely an example, and the techniques of this application may be applicable to video encoding settings (e.g., video encoding or video decoding) that do not necessarily involve any data communication between the encoding and decoding devices. In other examples, the data may be retrieved from local storage, streamed over a network, and so on. A video encoding device may encode and store data to a memory, and/or a video decoding device may retrieve and decode data from a memory. In some examples, the encoding and decoding are performed by devices that do not communicate with each other, but merely encode data to and/or retrieve data from memory and decode data.

It should be understood that for each of the examples described above with reference to video encoder 20, video decoder 30 may be used to perform the reverse process. With respect to signaling syntax elements, video decoder 30 may be configured to receive and parse such syntax elements and decode the associated video data accordingly. In some examples of the present invention, video encoder 20 may entropy encode into the encoded video bitstream one or more syntax elements defining a particular position of a fusion candidate in a fusion candidate list and syntax elements of an inter-coding type of a spatial non-neighboring block of the current block. In such instances, video decoder 30 may parse such syntax elements and decode the relevant video data accordingly.

Encoder and encoding method

Fig. 2 shows a schematic/conceptual block diagram of an example of a video encoder 20 for implementing the techniques of this disclosure. In the example of fig. 2, video encoder 20 includes a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a buffer 216, a loop filter unit 220, a Decoded Picture Buffer (DPB) 230, a prediction processing unit 260, and an entropy encoding unit 270. Prediction processing unit 260 may include inter prediction unit 244, intra prediction unit 254, and mode selection unit 262. Inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown). The video encoder 20 shown in fig. 2 may also be referred to as a hybrid video encoder or a video encoder according to a hybrid video codec.

For example, the residual calculation unit 204, the transform processing unit 206, the quantization unit 208, the prediction processing unit 260, and the entropy encoding unit 270 form a forward signal path of the encoder 20, and, for example, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the Decoded Picture Buffer (DPB) 230, the prediction processing unit 260 form a backward signal path of the encoder, wherein the backward signal path of the encoder corresponds to a signal path of a decoder (see the decoder 30 in fig. 3).

Encoder 20 receives picture 201 or block 203 of picture 201, e.g., a picture in a sequence of pictures forming a video or video sequence, e.g., via input 202. Picture block 203 may also be referred to as a current picture block or a picture block to be encoded, and picture 201 may be referred to as a current picture or a picture to be encoded (especially when the current picture is distinguished from other pictures in video encoding, such as previously encoded and/or decoded pictures in the same video sequence, i.e., a video sequence that also includes the current picture).

Segmentation

An embodiment of encoder 20 may include a partitioning unit (not shown in fig. 2) for partitioning picture 201 into a plurality of blocks, e.g., block 203, typically into a plurality of non-overlapping blocks. The partitioning unit may be used to use the same block size for all pictures in a video sequence and a corresponding grid defining the block size, or to alter the block size between pictures or subsets or groups of pictures and partition each picture into corresponding blocks. A quad-tree-binary-tree (QTBT) partitioning technique proposed by j.an et al in a Block partitioning structure for next generation video coding (international telecommunications union, COM16-C966, 9 months 2015, hereinafter referred to as "VCEG recommendation COM 16-C966") was introduced in VVC. Simulations have shown that the proposed QTBT structure is more efficient than the quadtree structure in HEVC used. Furthermore, in QTBT, a CU may have a square or rectangular shape. As shown in fig. 3, a Coding Tree Unit (CTU) is first divided by a quad tree structure. The leaf nodes of the quadtree may be further partitioned by a binary tree structure. There are two partition types in binary tree partitioning: symmetrical horizontal division and symmetrical vertical division. In each case, the nodes are divided by horizontally or vertically bisecting the nodes along the middle. The binary tree leaf nodes are called Coding Units (CUs) and are each processed for prediction and transformation without any further partitioning. This means that CU, PU and TU have the same block size in the QTBT coding block structure. CUs are sometimes made up of Coded Blocks (CBs) with different color components, for example, in 4: 2: in the case of P, B slices of the 0 chroma format, one CU contains one luma CB and two chroma CBs, and sometimes a CU consists of CBs having a single component, e.g., in the case of I slices, one CU contains only one luma CB or only two chroma CBs.

In addition, a block division structure named a multi-type-tree (MTT) is proposed in U.S. patent application publication No. 20170208336 in place of the QT, BT and/or QTBT based CU structure. The MTT partition structure is still a recursive tree structure. In MTT, a plurality of different partition structures (e.g., three or more) are used. For example, according to the MTT technique, three or more different partitioning structures may be used at each depth of the tree structure for each respective non-leaf node of the tree structure. The depth of a node in the tree structure may refer to the length of the path (e.g., number of splits) from the node to the root of the tree structure. The partition structure may generally refer to how many different blocks a block may be divided into. The partition structure may be a quad tree partition structure that may divide a block into four blocks, a binary tree partition structure that may divide a block into two blocks, or a tri tree partition structure that may divide a block into three blocks, and furthermore, the tri tree partition structure may not divide a block through the center. The partition structure may have a plurality of different partition types. The partition type may additionally define how the blocks are partitioned, including symmetric or asymmetric partitions, uniform or non-uniform partitions, and/or horizontal or vertical partitions.

In MTT, at each depth of the tree structure, the encoder 100 may be used to further partition the subtree using a particular partition type of one of three additional partition structures. For example, the encoder 100 may be used to determine a particular partition type from QT, BT, triple-tree (TT), and other partition structures. In one example, the QT partition structure may contain a square quadtree or a rectangular quadtree partition type. The encoder 100 may use square quadtree partitioning to partition square blocks by dividing the block into four equally sized square blocks horizontally and vertically along the center. Likewise, the encoder 100 may use rectangular quadtree partitioning to partition a rectangular (e.g., non-square) block by dividing the rectangular block horizontally and vertically along the center into four equally sized rectangular blocks.

The BT partition structure may include at least one of a horizontally symmetric binary tree, a vertically symmetric binary tree, a horizontally asymmetric binary tree, or a vertically asymmetric binary tree partition type. For the horizontal symmetric binary tree splitting type, the encoder 100 may be used to split a block horizontally into two symmetric blocks of the same size along the center of the block. For the vertical symmetric binary tree partition type, the encoder 100 may be used to vertically bisect a block into two symmetric blocks of the same size along the center of the block. For the horizontally asymmetric binary tree partition type, the encoder 100 may be used to horizontally partition a block into two blocks of different sizes. For example, one block may be 1/4 of a parent block size, while another block may be 3/4 of a parent block size, similar to PART _2N × nU or PART _2N × nD partition types. For the vertical asymmetric binary tree partition type, the encoder 100 may be used to vertically partition a block into two blocks of different sizes. For example, one block may be 1/4 of a parent block size, while another block may be 3/4 of a parent block size, similar to a PART _ nL × 2N or PART _ nR × 2N partition type. In other examples, the asymmetric binary tree partition type may partition a parent block into different sized portions. For example, one child block may be 3/8 of the parent block, while another child block may be 5/8 of the parent block. Of course, such division type may be a vertical type or a horizontal type.

The TT-split structure differs from the type of QT or BT structure in that it does not split blocks along the center. The central regions of the blocks are kept together in the same sub-block. Instead of generating a QT for four blocks or generating a binary tree for two blocks, the partitioning according to the TT partitioning structure generates three blocks. Example partition types of the partition structure according to TT include a symmetric partition type (both horizontal and vertical) and an asymmetric partition type (both horizontal and vertical). Further, the symmetric division type according to the TT division structure may be unequal/uneven or equal/even. The asymmetric partition type according to the TT partition structure is not uniform/uniform. In one example, the TT partition structure may contain at least one of the following partition types: a horizontal equal/uniform symmetric ternary tree, a vertical equal/uniform symmetric ternary tree, a horizontal unequal/non-uniform symmetric ternary tree, a vertical unequal/non-uniform symmetric ternary tree, a horizontal unequal/non-uniform asymmetric ternary tree, or a vertical unequal/non-uniform asymmetric ternary tree partition type.

In general, an unequal/unequal symmetric trie partition type is one that is symmetric about a block's centerline but in which at least one of the resulting three blocks is not the same size as the other two. One preferred example is where the side blocks are block sizes 1/4 and the center block is a block size 1/2. The equal/uniform symmetric treble partition type is a partition type that is symmetric around the center line of a block and the sizes of the resulting blocks are all the same. Such a division is possible if the block height or width, depending on the vertical or horizontal division, is an integer multiple of 3. An unequal/unequal asymmetric ternary tree partition type is a partition type that is not symmetric about a centerline of a block and in which at least one of the resulting blocks is not equally sized to the other two.

In one example, prediction processing unit 260 of video encoder 20 may be used to perform any combination of the above-described segmentation techniques.

Like picture 201, block 203 is also or can be viewed as a two-dimensional array or matrix of sample points having intensity values (sample values), although smaller in size than picture 201. In other words, the block 203 may comprise, for example, one sample array (e.g., a luma array in the case of a black and white picture 201) or three sample arrays (e.g., a luma array and two chroma arrays in the case of a color picture) or any other number and/or class of arrays depending on the color format applied. The number of sampling points in the horizontal and vertical directions (or axes) of the block 203 defines the size of the block 203.

The encoder 20 as shown in fig. 2 is used to encode a picture 201 block by block, e.g., performing encoding and prediction for each block 203.

Residual calculation

The residual calculation unit 204 is configured to calculate a residual block 205 based on the picture block 203 and the prediction block 265 (further details of the prediction block 265 are provided below), e.g. by subtracting sample values of the picture block 203 from sample values of the prediction block 265 on a sample-by-sample (pixel-by-pixel) basis to obtain the residual block 205 in the sample domain.

Transformation of

The transform processing unit 206 is configured to apply a transform, such as a Discrete Cosine Transform (DCT) or a Discrete Sine Transform (DST), on the sample values of the residual block 205 to obtain transform coefficients 207 in a transform domain. The transform coefficients 207 may also be referred to as transform residual coefficients and represent the residual block 205 in the transform domain.

The transform processing unit 206 may be used to apply integer approximations of DCT/DST, such as the transform specified for HEVC/h.265. Such integer approximations are typically scaled by some factor compared to the orthogonal DCT transform. To maintain the norm of the residual block processed by the forward transform and the inverse transform, an additional scaling factor is applied as part of the transform process. The scaling factor is typically selected based on certain constraints, e.g., the scaling factor is a power of 2 for a shift operation, a trade-off between bit depth of transform coefficients, accuracy and implementation cost, etc. For example, a specific scaling factor may be specified on the decoder 30 side for the inverse transform by, for example, inverse transform processing unit 212 (and on the encoder 20 side for the corresponding inverse transform by, for example, inverse transform processing unit 212), and correspondingly, a corresponding scaling factor may be specified on the encoder 20 side for the forward transform by transform processing unit 206.

Quantization

Quantization unit 208 is used to quantize transform coefficients 207, e.g., by applying scalar quantization or vector quantization, to obtain quantized transform coefficients 209. Quantized transform coefficients 209 may also be referred to as quantized residual coefficients 209. The quantization process may reduce the bit depth associated with some or all of transform coefficients 207. For example, an n-bit transform coefficient may be rounded down to an m-bit transform coefficient during quantization, where n is greater than m. The quantization level may be modified by adjusting a Quantization Parameter (QP). For example, for scalar quantization, different scales may be applied to achieve finer or coarser quantization. Smaller quantization steps correspond to finer quantization and larger quantization steps correspond to coarser quantization. An appropriate quantization step size may be indicated by a Quantization Parameter (QP). For example, the quantization parameter may be an index of a predefined set of suitable quantization step sizes. For example, a smaller quantization parameter may correspond to a fine quantization (smaller quantization step size) and a larger quantization parameter may correspond to a coarse quantization (larger quantization step size), or vice versa. The quantization may comprise a division by a quantization step size and a corresponding quantization or inverse quantization, e.g. performed by inverse quantization 210, or may comprise a multiplication by a quantization step size. Embodiments according to some standards, such as HEVC, may use a quantization parameter to determine the quantization step size. In general, the quantization step size may be calculated based on the quantization parameter using a fixed point approximation of an equation that includes division. Additional scaling factors may be introduced for quantization and dequantization to recover the norm of the residual block that may be modified due to the scale used in the fixed point approximation of the equation for the quantization step size and quantization parameter. In one example implementation, the inverse transform and inverse quantization scales may be combined. Alternatively, a custom quantization table may be used and signaled from the encoder to the decoder, e.g., in a bitstream. Quantization is a lossy operation, where the larger the quantization step size, the greater the loss.

The inverse quantization unit 210 is configured to apply inverse quantization of the quantization unit 208 on the quantized coefficients to obtain inverse quantized coefficients 211, e.g., to apply an inverse quantization scheme of the quantization scheme applied by the quantization unit 208 based on or using the same quantization step as the quantization unit 208. The dequantized coefficients 211 may also be referred to as dequantized residual coefficients 211, corresponding to transform coefficients 207, although the loss due to quantization is typically not the same as the transform coefficients.

The inverse transform processing unit 212 is configured to apply an inverse transform of the transform applied by the transform processing unit 206, for example, an inverse Discrete Cosine Transform (DCT) or an inverse Discrete Sine Transform (DST), to obtain an inverse transform block 213 in the sample domain. The inverse transform block 213 may also be referred to as an inverse transform dequantized block 213 or an inverse transform residual block 213.

The reconstruction unit 214 (e.g., summer 214) is used to add the inverse transform block 213 (i.e., the reconstructed residual block 213) to the prediction block 265 to obtain the reconstructed block 215 in the sample domain, e.g., to add sample values of the reconstructed residual block 213 to sample values of the prediction block 265.

Optionally, a buffer unit 216 (or simply "buffer" 216), such as a line buffer 216, is used to buffer or store the reconstructed block 215 and corresponding sample values, for example, for intra prediction. In other embodiments, the encoder may be used to use the unfiltered reconstructed block and/or corresponding sample values stored in buffer unit 216 for any class of estimation and/or prediction, such as intra prediction.

For example, an embodiment of encoder 20 may be configured such that buffer unit 216 is used not only to store reconstructed blocks 215 for intra prediction 254, but also for loop filter unit 220 (not shown in fig. 2), and/or such that buffer unit 216 and decoded picture buffer unit 230 form one buffer, for example. Other embodiments may be used to use filtered block 221 and/or blocks or samples from decoded picture buffer 230 (neither shown in fig. 2) as input or basis for intra prediction 254.

The loop filter unit 220 (or simply "loop filter" 220) is used to filter the reconstructed block 215 to obtain a filtered block 221, so as to facilitate pixel transition or improve video quality. Loop filter unit 220 is intended to represent one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or other filters, such as a bilateral filter, an Adaptive Loop Filter (ALF), or a sharpening or smoothing filter, or a collaborative filter. Although loop filter unit 220 is shown in fig. 2 as an in-loop filter, in other configurations, loop filter unit 220 may be implemented as a post-loop filter. The filtered block 221 may also be referred to as a filtered reconstructed block 221. The decoded picture buffer 230 may store the reconstructed encoded block after the loop filter unit 220 performs a filtering operation on the reconstructed encoded block.

Embodiments of encoder 20 (correspondingly, loop filter unit 220) may be configured to output loop filter parameters (e.g., sample adaptive offset information), e.g., directly or after entropy encoding by entropy encoding unit 270 or any other entropy encoding unit, e.g., such that decoder 30 may receive and apply the same loop filter parameters for decoding.

Decoded Picture Buffer (DPB) 230 may be a reference picture memory that stores reference picture data for use by video encoder 20 in encoding video data. DPB 230 may be formed from any of a variety of memory devices, such as Dynamic Random Access Memory (DRAM) including Synchronous DRAM (SDRAM), Magnetoresistive RAM (MRAM), Resistive RAM (RRAM), or other types of memory devices. The DPB 230 and the buffer 216 may be provided by the same memory device or separate memory devices. In a certain example, a Decoded Picture Buffer (DPB) 230 is used to store filtered blocks 221. Decoded picture buffer 230 may further be used to store other previously filtered blocks, such as previously reconstructed and filtered blocks 221, of the same current picture or of a different picture, such as a previously reconstructed picture, and may provide the complete previously reconstructed, i.e., decoded picture (and corresponding reference blocks and samples) and/or partially reconstructed current picture (and corresponding reference blocks and samples), e.g., for inter prediction. In a certain example, if reconstructed block 215 is reconstructed without in-loop filtering, Decoded Picture Buffer (DPB) 230 is used to store reconstructed block 215.

Prediction processing unit 260, also referred to as block prediction processing unit 260, is used to receive or obtain block 203 (current block 203 of current picture 201) and reconstructed picture data, e.g., reference samples of the same (current) picture from buffer 216 and/or reference picture data 231 of one or more previously decoded pictures from decoded picture buffer 230, and to process such data for prediction, i.e., to provide prediction block 265, which may be inter-predicted block 245 or intra-predicted block 255.

The mode selection unit 262 may be used to select a prediction mode (e.g., intra or inter prediction mode) and/or a corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.

Embodiments of mode selection unit 262 may be used to select prediction modes (e.g., from those supported by prediction processing unit 260) that provide the best match or the smallest residual (smallest residual means better compression in transmission or storage), or that provide the smallest signaling overhead (smallest signaling overhead means better compression in transmission or storage), or both. The mode selection unit 262 may be configured to determine a prediction mode based on Rate Distortion Optimization (RDO), i.e., select a prediction mode that provides the minimum rate distortion optimization, or select a prediction mode in which the associated rate distortion at least meets the prediction mode selection criteria.

The prediction processing performed by the example of the encoder 20 (e.g., by the prediction processing unit 260) and the mode selection performed (e.g., by the mode selection unit 262) will be explained in detail below.

As described above, the encoder 20 is configured to determine or select the best or optimal prediction mode from a set of (predetermined) prediction modes. The prediction mode set may include, for example, intra prediction modes and/or inter prediction modes.

The intra prediction mode set may include 35 different intra prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in h.265, or may include 67 different intra prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in h.266 under development.

The set of (possible) inter prediction modes depends on the available reference pictures (i.e. at least partially decoded pictures stored in the DBP 230, e.g. as described above) and other inter prediction parameters, e.g. on whether the best matching reference block is searched using the entire reference picture or only a part of the reference picture, e.g. a search window area of an area surrounding the current block, and/or e.g. on whether pixel interpolation like half-pixel and/or quarter-pixel interpolation is applied.

In addition to the above prediction mode, a skip mode and/or a direct mode may also be applied.

The prediction processing unit 260 may further be configured to partition the block 203 into smaller block partitions or sub-blocks, for example, by iteratively using quad-tree (QT) partitions, binary-tree (BT) partitions, or triple-tree (TT) partitions, or any combination thereof, and to perform prediction, for example, for each of the block partitions or sub-blocks, wherein mode selection includes selecting a tree structure of the partitioned block 203 and selecting a prediction mode to apply to each of the block partitions or sub-blocks.

The inter prediction unit 244 may include a Motion Estimation (ME) unit (not shown in fig. 2) and a Motion Compensation (MC) unit (not shown in fig. 2). The motion estimation unit is used to receive or obtain picture block 203 (current picture block 203 of current picture 201) and decoded picture 231, or at least one or more previously reconstructed blocks, e.g., reconstructed blocks of one or more other/different previously decoded pictures 231, for motion estimation. For example, the video sequence may comprise a current picture and a previously decoded picture 31, or in other words, the current picture and the previously decoded picture 31 may be part of, or form, a sequence of pictures forming the video sequence. The construction of the fusion candidate list of the present application can be realized by the motion estimation module.

For example, the encoder 20 may be configured to select a reference block from among a plurality of reference blocks of the same or different ones of a plurality of other pictures, and provide the reference picture (or reference picture index … …) and/or an offset (spatial offset) between a position (X, Y coordinates) of the reference block and a position of the current block to a motion estimation unit (not shown in fig. 2) as an inter prediction parameter. This offset is also called a Motion Vector (MV).

The motion compensation unit is used to obtain, e.g., receive, inter-prediction parameters and perform inter-prediction based on or using the inter-prediction parameters to obtain the inter-prediction block 245. The motion compensation performed by the motion compensation unit (not shown in fig. 2) may involve taking or generating a prediction block based on a motion/block vector determined by motion estimation (possibly performing interpolation to sub-pixel precision). Interpolation filtering may generate additional pixel samples from known pixel samples, potentially increasing the number of candidate prediction blocks that may be used to encode a picture block. Upon receiving the motion vector for the PU of the current picture block, motion compensation unit 246 may locate the prediction block in one reference picture list to which the motion vector points. Motion compensation unit 246 may also generate syntax elements associated with the blocks and video slices for use by video decoder 30 in decoding picture blocks of the video slices.

The intra prediction unit 254 is used to obtain, e.g., receive, the picture block 203 (current picture block) of the same picture and one or more previously reconstructed blocks, e.g., reconstructed neighboring blocks, for intra estimation. For example, the encoder 20 may be configured to select an intra-prediction mode from a plurality of (predetermined) intra-prediction modes.

Embodiments of encoder 20 may be used to select an intra prediction mode based on optimization criteria, such as based on a minimum residual (e.g., an intra prediction mode that provides a prediction block 255 that is most similar to current picture block 203) or a minimum code rate distortion (e.g., … …).

The intra-prediction unit 254 is further configured to determine the intra-prediction block 255 based on the intra-prediction parameters as the selected intra-prediction mode. In any case, after selecting the intra-prediction mode for the block, intra-prediction unit 254 is also used to provide intra-prediction parameters, i.e., information indicating the selected intra-prediction mode for the block, to entropy encoding unit 270. In one example, intra-prediction unit 254 may be used to perform any combination of the intra-prediction techniques described below.

Entropy encoding unit 270 is configured to apply an entropy encoding algorithm or scheme (e.g., a Variable Length Coding (VLC) scheme, a Context Adaptive VLC (CAVLC) scheme, an arithmetic coding scheme, a Context Adaptive Binary Arithmetic Coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), Probability Interval Partitioning Entropy (PIPE) coding, or other entropy encoding methods or techniques) to individual or all of quantized residual coefficients 209, inter-prediction parameters, intra-prediction parameters, and/or loop filter parameters (or not) to obtain encoded picture data 21 that may be output by output 272 in the form of, for example, encoded bitstream 21. The encoded bitstream may be transmitted to video decoder 30, or archived for later transmission or retrieval by video decoder 30. Entropy encoding unit 270 may also be used to entropy encode other syntax elements of the current video slice being encoded.

Other structural variations of video encoder 20 may be used to encode the video stream. For example, the non-transform based encoder 20 may quantize the residual signal directly without the transform processing unit 206 for certain blocks or frames. In another embodiment, encoder 20 may have quantization unit 208 and inverse quantization unit 210 combined into a single unit.

Fig. 3 illustrates an exemplary video decoder 30 for implementing the techniques of the present application, namely performing fusion candidate list construction of a block to be decoded (current block) and decoding of a compressed image based on the constructed fusion candidate list. Video decoder 30 is operative to receive encoded picture data (e.g., an encoded bitstream) 21, e.g., encoded by encoder 20, to obtain a decoded picture 231. During the decoding process, video decoder 30 receives video data, such as an encoded video bitstream representing picture blocks of an encoded video slice and associated syntax elements, from video encoder 20.

In the example of fig. 3, decoder 30 includes entropy decoding unit 304, inverse quantization unit 310, inverse transform processing unit 312, reconstruction unit 314 (e.g., summer 314), buffer 316, loop filter 320, decoded picture buffer 330, and prediction processing unit 360. The prediction processing unit 360 may include an inter prediction unit 344, an intra prediction unit 354, and a mode selection unit 362. In some examples, video decoder 30 may perform a decoding pass that is substantially reciprocal to the encoding pass described with reference to video encoder 20 of fig. 2.

Entropy decoding unit 304 is to perform entropy decoding on encoded picture data 21 to obtain, for example, quantized coefficients 309 and/or decoded encoding parameters (not shown in fig. 3), such as any or all of inter-prediction, intra-prediction parameters, loop filter parameters, and/or other syntax elements (decoded). The entropy decoding unit 304 is further for forwarding the inter-prediction parameters, the intra-prediction parameters, and/or other syntax elements to the prediction processing unit 360. Video decoder 30 may receive syntax elements at the video slice level and/or the video block level.

Inverse quantization unit 310 may be functionally identical to inverse quantization unit 110, inverse transform processing unit 312 may be functionally identical to inverse transform processing unit 212, reconstruction unit 314 may be functionally identical to reconstruction unit 214, buffer 316 may be functionally identical to buffer 216, loop filter 320 may be functionally identical to loop filter 220, and decoded picture buffer 330 may be functionally identical to decoded picture buffer 230.

Prediction processing unit 360 may include inter prediction unit 344 and intra prediction unit 354, where inter prediction unit 344 may be functionally similar to inter prediction unit 244 and intra prediction unit 354 may be functionally similar to intra prediction unit 254. The prediction processing unit 360 is typically used to perform block prediction and/or to obtain a prediction block 365 from the encoded data 21, as well as to receive or obtain (explicitly or implicitly) prediction related parameters and/or information about the selected prediction mode from, for example, the entropy decoding unit 304.

When the video slice is encoded as an intra-coded (I) slice, intra-prediction unit 354 of prediction processing unit 360 is used to generate a prediction block 365 for the picture block of the current video slice based on the signaled intra-prediction mode and data from previously decoded blocks of the current frame or picture. When a video frame is encoded as an inter-coded (i.e., B or P) slice, inter prediction unit 344 (e.g., a motion compensation unit) of prediction processing unit 360 is used to generate a prediction block 365 for the video block of the current video slice based on the motion vectors and other syntax elements received from entropy decoding unit 304. For inter prediction, a prediction block may be generated from one reference picture within one reference picture list. Video decoder 30 may construct the reference frame list using default construction techniques based on the reference pictures stored in DPB 330: list 0 and list 1.

Prediction processing unit 360 is used to determine prediction information for the video blocks of the current video slice by parsing the motion vectors and other syntax elements, and to generate a prediction block for the current video block being decoded using the prediction information. For example, prediction processing unit 360 uses some of the syntax elements received to determine a prediction mode (e.g., intra or inter prediction) for encoding video blocks of a video slice, an inter prediction slice type (e.g., B-slice, P-slice, or GPB-slice), construction information for one or more of a reference picture list of the slice, a motion vector for each inter-coded video block of the slice, an inter prediction state for each inter-coded video block of the slice, and other information to decode video blocks of the current video slice.

Inverse quantization unit 310 may be used to inverse quantize (i.e., inverse quantize) the quantized transform coefficients provided in the bitstream and decoded by entropy decoding unit 304. The inverse quantization process may include using quantization parameters calculated by video encoder 20 for each video block in the video slice to determine the degree of quantization that should be applied and likewise the degree of inverse quantization that should be applied.

Inverse transform processing unit 312 is used to apply an inverse transform (e.g., an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process) to the transform coefficients in order to produce a block of residuals in the pixel domain.

The reconstruction unit 314 (e.g., summer 314) is used to add the inverse transform block 313 (i.e., reconstructed residual block 313) to the prediction block 365 to obtain the reconstructed block 315 in the sample domain, e.g., by adding sample values of the reconstructed residual block 313 to sample values of the prediction block 365.

Loop filter unit 320 (either during or after the encoding cycle) is used to filter reconstructed block 315 to obtain filtered block 321 to facilitate pixel transitions or improve video quality. Loop filter unit 320 is intended to represent one or more loop filters such as a deblocking filter, a sample-adaptive offset (SAO) filter, or other filters such as a bilateral filter, an Adaptive Loop Filter (ALF), or a sharpening or smoothing filter, or a collaborative filter. Although loop filter unit 320 is shown in fig. 3 as an in-loop filter, in other configurations, loop filter unit 320 may be implemented as a post-loop filter.

Decoded video block 321 in a given frame or picture is then stored in decoded picture buffer 330, which stores reference pictures for subsequent motion compensation.

Decoder 30 is used to output decoded picture 31, e.g., via output 332, for presentation to or viewing by a user.

Other variations of video decoder 30 may be used to decode the compressed bitstream. For example, decoder 30 may generate an output video stream without loop filter unit 320. For example, the non-transform based decoder 30 may directly inverse quantize the residual signal without the inverse transform processing unit 312 for certain blocks or frames. In another embodiment, video decoder 30 may have inverse quantization unit 310 and inverse transform processing unit 312 combined into a single unit.

Fig. 4 is an illustration of an example of a video encoding system 40 including encoder 20 of fig. 2 and/or decoder 30 of fig. 3, according to an example embodiment. The system 40 may implement the techniques of the present application for constructing a fusion candidate list of a current block based on the fusion candidate construction method proposed by the present invention, and encoding or decoding an image based on the fusion candidate list. In the illustrated embodiment, video encoding system 40 may include an imaging device 41, video encoder 20, video decoder 30 (and/or a video encoder implemented by logic 47 of processing unit 46), an antenna 42, one or more processors 43, one or more memories 44, and/or a display device 45.

As shown, the imaging device 41, the antenna 42, the processing unit 46, the logic circuit 47, the video encoder 20, the video decoder 30, the processor 43, the memory 44, and/or the display device 45 are capable of communicating with each other. As discussed, although video encoding system 40 is shown with video encoder 20 and video decoder 30, in different examples, video encoding system 40 may include only video encoder 20 or only video decoder 30.

In some examples, as shown, video encoding system 40 may include an antenna 42. For example, the antenna 42 may be used to transmit or receive an encoded bitstream of video data. Additionally, in some examples, video encoding system 40 may include a display device 45. Display device 45 may be used to present video data. In some examples, logic 47 may be implemented by processing unit 46, as shown. The processing unit 46 may comprise application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, or the like. Video coding system 40 may also include an optional processor 43, which optional processor 43 similarly may include application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, or the like. In some examples, the logic 47 may be implemented in hardware, such as video encoding specific hardware, and the processor 43 may be implemented in general purpose software, an operating system, and so on. In addition, the Memory 44 may be any type of Memory, such as a volatile Memory (e.g., Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), etc.), a nonvolatile Memory (e.g., flash Memory, etc.), and the like. In a non-limiting example, storage 44 may be implemented by a speed cache memory. In some instances, logic circuitry 47 may access memory 44 (e.g., to implement an image buffer). In other examples, logic 47 and/or processing unit 46 may include memory (e.g., cache, etc.) for implementing image buffers, etc.

In some examples, video encoder 20 implemented by logic circuitry may include an image buffer (e.g., implemented by processing unit 46 or memory 44) and a graphics processing unit (e.g., implemented by processing unit 46). The graphics processing unit may be communicatively coupled to the image buffer. The graphics processing unit may include video encoder 20 implemented by logic circuitry 47 to implement the various modules discussed with reference to fig. 2 and/or any other encoder system or subsystem described herein. Logic circuitry may be used to perform various operations discussed herein.

Video decoder 30 may be implemented in a similar manner by logic circuitry 47 to implement the various modules discussed with reference to decoder 30 of fig. 3 and/or any other decoder system or subsystem described herein. In some examples, logic circuit implemented video decoder 30 may include an image buffer (implemented by processing unit 2820 or memory 44) and a graphics processing unit (e.g., implemented by processing unit 46). The graphics processing unit may be communicatively coupled to the image buffer. The graphics processing unit may include video decoder 30 implemented by logic circuitry 47 to implement the various modules discussed with reference to fig. 3 and/or any other decoder system or subsystem described herein.

In some examples, antenna 42 of video encoding system 40 may be used to receive an encoded bitstream of video data. As discussed, the encoded bitstream may include data related to the encoded video frame, indicators, index values, mode selection data, etc., discussed herein, such as data related to the encoding partition (e.g., transform coefficients or quantized transform coefficients, (as discussed) optional indicators, and/or data defining the encoding partition). Video encoding system 40 may also include a video decoder 30 coupled to antenna 42 and configured to decode the encoded bitstream. The display device 45 is used to present video frames.

Fig. 5 is a simplified block diagram of an apparatus 500 that may be used as either or both of source device 12 and destination device 14 in fig. 1, according to an example embodiment. The apparatus 500 may implement the techniques of the present application for performing construction of a fusion candidate list and encoding or decoding of an image based on the constructed fusion candidate list. The apparatus 500 may take the form of a computing system including multiple computing devices or a single computing device such as a mobile phone, tablet computer, laptop computer, notebook computer, desktop computer, or the like.

The processor 502 in the apparatus 500 may be a central processor. Alternatively, processor 502 may be any other type of device or devices now or later developed that is capable of manipulating or processing information. As shown, although the disclosed embodiments may be practiced using a single processor, such as processor 502, speed and efficiency advantages may be realized using more than one processor.

In one embodiment, the Memory 504 of the apparatus 500 may be a Read Only Memory (ROM) device or a Random Access Memory (RAM) device. Any other suitable type of storage device may be used for memory 504. The memory 504 may include code and data 506 that is accessed by the processor 502 using a bus 512. The memory 504 may further include an operating system 508 and application programs 510, the application programs 510 including at least one program that permits the processor 502 to perform the methods described herein. For example, applications 510 may include applications 1 through N, with applications 1 through N further including a video encoding application that performs the fusion candidate list construction described herein. The apparatus 500 may also include additional memory in the form of a slave memory 514, the slave memory 514 may be, for example, a memory card for use with a mobile computing device. Because a video communication session may contain a large amount of information, this information may be stored in whole or in part in the slave memory 514 and loaded into the memory 504 for processing as needed.

Device 500 may also include one or more output apparatuses, such as a display 518. In one example, display 518 may be a touch-sensitive display that combines a display and a touch-sensitive element operable to sense touch inputs. A display 518 may be coupled to the processor 502 via the bus 512. Other output devices that permit a user to program apparatus 500 or otherwise use apparatus 500 may be provided in addition to display 518, or other output devices may be provided as an alternative to display 518. When the output device is or includes a display, the display may be implemented in different ways, including by a Liquid Crystal Display (LCD), a Cathode Ray Tube (CRT) display, a plasma display, or a Light Emitting Diode (LED) display, such as an Organic LED (OLED) display.

The apparatus 500 may also include or be in communication with an image sensing device 520, the image sensing device 520 being, for example, a camera or any other image sensing device 520 now or later developed that can sense an image, such as an image of a user running the apparatus 500. The image sensing device 520 may be placed directly facing the user running the apparatus 500. In an example, the position and optical axis of image sensing device 520 may be configured such that its field of view includes an area proximate display 518 and display 518 is visible from that area.

The apparatus 500 may also include or be in communication with a sound sensing device 522, such as a microphone or any other sound sensing device now known or later developed that can sense sound in the vicinity of the apparatus 500. The sound sensing device 522 may be positioned to face directly the user operating the apparatus 500 and may be used to receive sounds, such as speech or other utterances, emitted by the user while operating the apparatus 500.

Although the processor 502 and the memory 504 of the apparatus 500 are shown in fig. 5 as being integrated in a single unit, other configurations may also be used. The operations of processor 502 may be distributed among multiple directly couplable machines (each machine having one or more processors), or distributed in a local area or other network. Memory 504 may be distributed among multiple machines, such as a network-based memory or a memory among multiple machines running apparatus 500. Although only a single bus is shown here, the bus 512 of the apparatus 500 may be formed from multiple buses. Further, the secondary memory 514 may be directly coupled to other components of the apparatus 500 or may be accessible over a network and may comprise a single integrated unit, such as one memory card, or multiple units, such as multiple memory cards. Accordingly, the apparatus 500 may be implemented in a variety of configurations.

Fig. 11 is a flowchart of example operations of implementing a fusion candidate list construction method in an embodiment of the present invention by video encoder 20 and video decoder 30 according to fig. 1. One or more functional units of video encoder 20 or video decoder 30, including prediction processing unit 260/360, may be used to perform the method of fig. 11. In the example of fig. 11, an updating method for improving a historical motion information candidate list is proposed, which is applied to inter-frame prediction, allows the historical motion information candidate list to be reconstructed at a CTU (coding tree) level, is more beneficial to design the parallelism of line-level and CTU-level coding and decoding without increasing additional storage areas and with considerable coding efficiency, and can ensure that the coding and decoding time is greatly reduced when the coding quality is not substantially lost in the inter-frame coding process. The inter prediction method of the candidate list includes, with reference to fig. 11:

s1101 initializing a historical candidate motion information list corresponding to the current coding tree unit;

the historical candidate motion information list comprises N storage spaces, the N storage spaces are used for storing historical candidate motion information, the initialized historical candidate motion information list comprises at least M vacant storage spaces, M is not more than N, M and N are integers, the current coding tree unit is contained in a coding tree unit set (Slice) formed by a plurality of coding tree units, and the current coding tree unit is not the first one in the coding tree unit set according to a preset processing sequence;

s1103, adding motion information at L positions in an adjacent space domain block of the current coding tree unit to the historical candidate motion information list according to a preset sequence, wherein M is more than or equal to L which is more than or equal to N, and the L positions in the adjacent space domain block are obtained according to a preset rule;

s1105, constructing a current candidate motion information list of the current coding tree unit or a current candidate motion information list of the current coding unit, wherein the coding units are obtained by dividing the coding tree unit; and

s1107 performs inter prediction on the current coding tree unit or the current coding unit according to a combination of the current candidate motion information list and the history candidate motion information list of the current coding tree unit or a combination of the current candidate motion information list and the history candidate motion information list of the current coding unit.

Optionally, the initializing the historical candidate motion information list corresponding to the current coding tree unit includes clearing the historical candidate motion information list so that M is equal to N, in such a way that the current coding tree unit can construct a completely new historical candidate motion information list to increase accuracy of inter-frame prediction.

Optionally, the M positions in the adjacent spatial blocks are obtained by obtaining a first candidate motion information from a preset position in the adjacent spatial block, taking the position where the first candidate motion information is obtained as a starting point, and obtaining the remaining M-1 candidate motion information at intervals of a preset step length. In order to be unified with the existing historical candidate motion information list construction mode and have a simplified algorithm in the process of constructing the historical candidate motion information list, the motion vectors at the M positions are usually obtained sequentially from a starting point position at preset intervals, where the preset intervals may also be referred to as step sizes, and the step sizes may be fixed, for example, using 4 or 8 pixels as a unit; furthermore, the step size may also be varied, for example, different step sizes are set according to the size of the current coding tree unit. The adding order of the motion information/motion vector at the M position may be a preset order, for example, according to a clockwise order, taking the spatial neighboring block at the lower left corner of the current coding tree unit as a starting point, and taking the spatial neighboring block at the upper right corner of the current coding tree unit as an end point, adding the motion information at L positions in the spatial neighboring block to the historical candidate motion information list.

Optionally, before inter-predicting the current coding tree unit or the current coding unit according to a combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit, the method may further combine the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or combine the current candidate motion information list and the historical candidate motion information list of the current coding unit, which may specifically be: and adding the historical candidate motion information into a current candidate motion information list of the current coding tree unit or a current candidate motion information list of a previous coding unit, and then performing the inter-frame prediction based on the current candidate motion information list of the current coding tree unit or the current candidate motion information list of the previous coding unit.

If the current coding tree unit needs to be further divided into coding units for coding, the method may further include: acquiring motion information of the current coding unit according to a combination of a current candidate motion information list and the historical candidate motion information list of the current coding unit, and performing inter-frame prediction on the current coding unit according to the acquired motion information; and updating the historical candidate motion information list based on the current coding unit motion information. The method can continuously obtain and update the historical candidate motion information list corresponding to the current coding tree unit so as to improve the accuracy of inter-frame prediction. Optionally, the above-mentioned updating of the historical candidate motion information list may be divided into two cases, that is, if the M positions are not filled, adding the current coding unit motion information as historical motion information into an empty storage space closest to an N-M position among the M positions in the historical candidate motion information list; or; if the M positions are filled, removing the historical motion information which is added into the historical candidate motion information list at the earliest time according to a first-in first-out principle, shifting the position of the residual historical motion information which exceeds the removed historical motion information, and adding the motion information of the current coding unit as the historical motion information into the tail part of the historical candidate motion information list, wherein one end of the historical candidate motion information list, which contains the latest added historical motion information, is the tail part of the historical candidate motion information list. The method provides flexibility in the application of the historical candidate motion information list, that is, the historical candidate motion information list can be used for inter prediction of the current block when the historical candidate motion information list is not completely filled, and under the condition that the historical candidate motion information list is filled, the motion information/motion vector of the current coding block can still be used for updating the historical candidate motion information list. Certainly, under the condition that the historical candidate motion information list is full, the motion information/motion vector of the current coding block still can not update the historical candidate motion information list any more, that is, if the M positions are not full, the motion information of the current coding unit is added as the historical motion information into the empty storage space closest to the N-M position in the M positions in the historical candidate motion information list; and if the M positions are full, performing inter-frame prediction processing on the next coding unit based on the current candidate motion information list. This processing manner may allow parallel processing of the coding blocks within the current coding tree unit, and specifically may be inter-predicting another coding unit based on the same method as the current coding unit, wherein the another coding unit is located after the current coding unit and belongs to the coding tree unit with the current coding unit according to a preset processing order, and the historical motion information list adopted by inter-predicting of the another coding unit includes the historical motion information in the historical motion information list adopted by inter-predicting of the current coding unit.

The scheme of the invention allows the historical candidate motion information list to be reconstructed at the CTU (coding tree) level, has equivalent coding efficiency, is more favorable for designing the row level and CTU level coding and decoding parallelism, and can ensure that the coding and decoding time is greatly reduced when the coding quality is basically not lost in the interframe coding process.

The following is an example of an implementation of the inter prediction method of the present invention:

the first embodiment is as follows:

initializing a historical candidate motion information list when the current coding tree unit starts to be coded;

the initialization process of the historical candidate motion information list may refer to the prior art, for example, the process may be performed by the same method as the jfet-K0104 proposal (i.e., when a SLICE (SLICE) starts, the historical candidate motion information list is cleared), or may be performed by other initialization methods of the historical candidate motion information list, which is not limited in the present invention; in this embodiment, the initialization is to empty the historical candidate motion information list. The coding tree unit may be further divided or not, and the definition of the coding tree unit is consistent with that of the coding tree unit in HEVC and VVC, and is a macroblock (macroblock) in h.264. Hereinafter, a coding tree unit is used, which, if further divided, forms a plurality of coding units, and therefore, in this case, can also be understood as a combination of coding units.

Then, the motion information of the spatial neighboring blocks of the current coding tree unit is added to the historical candidate motion information list.

The motion information of the spatial domain adjacent image block includes the motion information (a, An) of the left spatial domain adjacent image block and the motion information (B, Bn, C) of the upper spatial domain adjacent image block, as shown in fig. 10. Bn and An in fig. 10 are motion information extracted in a predetermined rule from all upper and left adjacent coded/decoded image blocks. The predetermined rule may be a fixed interval M and N extraction (M and N are positive integers greater than 0), the interval M is suitable for extracting motion information in the left adjacent image block, the interval N is suitable for extracting motion information in the upper adjacent image block, or other extracted predetermined rule modes may be used, and the present invention does not relate to a specific extracted predetermined rule mode. The above-mentioned neighboring image blocks preferably refer to image blocks located in the same SLICE as the current coding tree unit.

If the historical motion information candidate list is not filled after the spatial domain neighboring image block is traversed, or if the current coding tree unit is located at the top of a frame of image, or if the current coding tree unit is located at the left of a frame of image, then the unfilled portion of the historical motion information candidate list may be processed by referring to any one of the following methods.

The method comprises the following steps:

and no motion information of any other source is filled, and the motion information of the current coding unit acquired when the current coding unit in the current coding tree unit is coded and decoded is used as the historical candidate motion information to be added into the historical candidate motion information list.

The second method comprises the following steps:

and filling motion information of the coding block at the preset non-adjacent position of the airspace of the current coding tree unit. The preset non-adjacent position can be a fixed interval with the adjacent position, and can also be a preset template.

The third method comprises the following steps:

and filling the coding block time domain motion information from the preset position in the reference frame, the position corresponding to the current coding tree unit and the position corresponding to the coding block adjacent to the current coding tree unit. The preset positions in the corresponding positions of the current coding tree unit can be extracted at fixed intervals or in a specific rule or sequence. The predetermined position in the corresponding positions of the current coding tree unit adjacent to the coding blocks can be a specific rule and a specific sequence.

The method four comprises the following steps:

and filling the coded block time domain motion information of a preset position in the corresponding position of the current coded tree unit and the corresponding position of the coded block of the preset non-adjacent position of the previous coded tree unit in the reference frame. The preset positions in the corresponding positions of the current preceding coding tree unit may be extracted at fixed intervals, or may be extracted in a specific rule or order. The preset position in the corresponding position of the coding block with the preset non-adjacent position of the current coding tree unit can be extracted in a specific order by a specific rule.

The method five comprises the following steps:

and filling the historical candidate motion information in the historical candidate motion information list of the coding tree unit adjacent to the current coding tree unit.

Adding a, An, B, Bn and C to the historical candidate motion information list in a predetermined order until all neighboring blocks are traversed to end, or until the number of the historical candidate motion information in the historical candidate motion information list exceeds a preset maximum value, wherein the predetermined order in which a, An, B, Bn and C are added to the historical candidate motion information list may be in the order of C, An and Bn, may also be in the order of C, A0, B0, a1, B1 until An and Bn, or may also be in other predetermined orders, and the present invention does not relate to a specific predetermined order. In this embodiment, the historical candidate motion information list is initialized when each coding tree unit starts coding, so that each coding tree unit does not need to wait for the last coding unit of the previous coding tree unit to complete coding before starting processing, but can perform processing in parallel with the previous coding tree unit, thereby greatly saving processing time.

Example two:

unlike the embodiment in which the historical candidate motion information list is initialized when the current coding tree unit starts to be coded, the present embodiment adds a preset number of motion information of spatial neighboring image blocks of the current coding tree unit to the historical candidate motion information list when the current coding tree unit starts to be coded, where the preset number is a positive integer greater than 0. One possible implementation manner of adding the motion information of the spatial domain adjacent image blocks of the preset number of current coding tree units into the historical candidate motion information list may be to additionally supplement a preset number of motion information as new historical candidate motion information on the basis of existing historical candidate motion information in the existing historical candidate motion information list, regardless of whether the historical candidate motion information list is filled or not filled; another possible implementation manner may be that a predetermined number of pieces of historical candidate motion information of the historical candidate motion information existing in the existing historical candidate motion information list are removed according to a predetermined rule, and then a predetermined number of pieces of motion information in the spatial domain neighboring image blocks of the current coding tree unit are added to the historical candidate motion information list as new historical candidate motion information.

Example three:

the embodiment is the first embodiment and the second embodiment, wherein the history candidate motion information list is initialized or applied to inter prediction of a current coding unit after reconstruction, and the embodiment specifically includes:

the method in the first embodiment or the second embodiment is adopted to update or reconstruct the historical candidate motion information list. The specific reconstruction method is shown in the first embodiment or the second embodiment;

(1) inter-frame prediction is carried out on at least one coding unit in the current coding tree unit or the current coding tree unit;

the inter-frame prediction is performed on at least one coding unit in the current coding tree unit or in the current coding tree unit, and one coding tree unit or coding unit comprises a luminance coding block and two chrominance coding blocks by taking the luminance block or the chrominance block contained in the coding unit or the coding tree unit as a basic processing unit. At least one color component (chroma or luma) encoded block in a previous coding tree unit or in a current coding tree unit that is performing an encoding or decoding process is referred to as a current block.

The inter prediction of at least one coding unit in or in the current coding tree unit may include:

(2) analyzing the inter-frame prediction mode of the current block, and if the current block is in the merge/skip mode, generating a fused motion information candidate list; and if the current CU or the current block is in an AMVP mode, generating a motion candidate motion vector prediction list.

Optionally, the historical candidate motion information in the historical candidate motion information list is added to the fused motion information candidate list or the candidate motion vector prediction list. It should be noted that, instead of adding the historical candidate motion information in the historical candidate motion information list to the fused motion information candidate list or the candidate motion vector prediction list, the historical candidate motion information list may be kept independent, and the historical candidate motion information list may be directly indexed when predicting the current block. If the historical candidate motion information in the historical candidate motion information list is added to the fused motion information candidate list, the method in the proposal of jfet-K0104 may be adopted, or other methods may be adopted to add the historical candidate motion information in the historical candidate motion information list to the fused motion information candidate list, which is not limited in the present invention. It should be noted that, if the historical candidate motion information is added to the fused motion information candidate list, the historical candidate motion information in the historical candidate motion information list may be located before other types of fused candidates, such as a bi-predictive merge candidate (bi-predictive merge candidate) and a zero motion vector merge candidate (zero motion vector merge candidate).

The detailed process of generating the fused motion information candidate list if the current block is in merge/skip mode is as follows.

The fused motion information candidate list is constructed based on the following candidates: a. a maximum of four spatial fusion motion information candidate lists derived from five spatial neighboring blocks; b. a temporal fusion motion information candidate derived from the two temporal parity blocks; c. further fused motion information candidates comprising combined bi-prediction candidates and zero motion vector candidates. The first candidate in the fused motion information candidate list is a spatial neighbor. According to the right part of fig. 6, by sequentially checking a1, B1, B0, a0, and B2 in this order, at most four candidates can be inserted in the merge list in the order. Some additional redundancy checks are performed before all motion data of neighboring blocks are considered as fused motion information candidates. These redundancy checks can be divided into two categories for two different purposes: a. avoiding the presence of candidates with redundant motion data in the list; b. preventing merging of two otherwise representable partitions that would generate redundant syntax.

When N is the number of spatial fusion motion information candidate lists, the complete redundancy check will be performed by

And comparing the secondary motion data.In the case of five potential spatial fusion motion information candidates, ten motion data comparisons would be required to ensure that all candidates in the merge list have different motion data. During the development of HEVC, the check for redundant motion data has been reduced to a subset, thereby maintaining coding efficiency while significantly reducing comparison logic. In the final design, no more than two comparisons are performed for each candidate, resulting in a total of five comparisons. Given the order of { A1, B1, B0, A0, B2}, B0 only examined B1, A0 only examined A1, and B2 only examined A1 and B1. In the embodiment of partition redundancy check, the bottom PU and the top PU of the 2 NxN partition are merged by selecting candidate B1. This will result in one CU with two PUs having the same motion data, which can be equally signaled as a 2 nx 2N CU. In general, this check applies to all second PUs of the rectangular and asymmetric partitions 2 NxN, 2 NxnU, 2 NxnD, Nx 2N, nR x 2N, and nLx 2N. It should be noted that for the spatial fusion motion information candidate list, only the redundancy check is performed, and the motion data is copied from the candidate block as it is. Therefore, no motion vector scaling is required here.

The motion vectors of the temporal fusion motion information candidate list are derived the same as for the TMVP. Since the fused motion information candidate list includes all motion data and the TMVP is only one motion vector, the derivation of the entire motion data depends only on the type of slice. For bi-predictive slices, the TMVP is obtained for each reference picture list. The prediction type is set to bi-directional prediction or to a list where TMVP is available, depending on the availability of TMVP for each list. All related reference picture indices are set equal to zero. Thus, for uni-directional prediction slices, only the TMVP of list 0 is obtained along with the reference picture index equal to zero.

When at least one TMVP is available and the temporal fusion motion information candidate list is added to the list, no redundancy check is performed. This makes the merge list construction independent of the co-located pictures, thereby improving the error resilience. Consider the case where the temporal fusion motion information candidate list would be redundant and therefore not included in the fusion motion information candidate list. In case of a missing co-located picture, the decoder cannot get the temporal candidate motion information and therefore does not check if it is redundant. The indices of all subsequent candidates will be affected by this.

The length of the fused motion information candidate list is fixed for parsing robustness reasons. After the spatial and temporal fused motion information candidate list has been added, it may happen that the list is not yet fixed in length. To compensate for the coding efficiency loss that occurs with non-length adaptive list index signaling, additional candidates are generated. Depending on the type of slice, at most two candidates can be used to fully populate the list: a. combining the bi-directional prediction candidates; b. zero motion vector candidates.

In bi-predictive slices, additional candidates may be generated based on existing candidates by combining the reference picture list 0 motion data of one candidate with the list 1 motion data of another candidate. This is done by copying Δ x from one candidate, the first candidate, etc₀、Δy₀、Δt₀And copying Δ x from another candidate, such as the second candidate₁、Δy₁、Δt₁To complete. The different combinations are predefined and given in table 1.1.

TABLE 1.1

After adding combined bi-prediction candidates or when the list is still incomplete for uni-prediction slices, zero motion vector candidates are computed to complete the list. All zero motion vector candidates have one zero-shift motion vector for a uni-predicted slice and two zero-shift motion vectors for a bi-predicted slice. The reference index is set equal to zero and incremented by one for each additional candidate until a maximum number of reference indices is reached. If this is the case, and there are other candidates missing, then a reference index equal to zero is used to create these candidates. For all further candidates, no redundancy checks are performed, as the results show that omitting these checks does not cause a loss in coding efficiency.

For each PU coded in inter-picture prediction mode, the so-called merge _ flag indicates that the block merge is used to derive motion data. merge idx further determines the candidates in the merge list that provide all the motion data needed for MCP. In addition to this PU level signaling, the number of candidates in the merge list is signaled in the slice header. Since the default value is five, it is expressed as a difference from five (five _ minus _ max _ num _ merge _ cand). Thus, five is signaled with a short codeword of 0, while using only one candidate is signaled with a longer codeword of 4. As for the impact on the fused motion information candidate list construction process, the whole process remains unchanged, but after the list contains the maximum number of fused motion information candidate lists, the process terminates. In the initial design, the maximum value of merge index coding is given by the number of spatial and temporal candidate motion information available in the list. The index may be efficiently encoded as a flag when, for example, only two candidates are available. However, in order to resolve the merge index, the entire list of fused motion information candidates must be built to know the actual number of candidates. Assuming that the neighboring blocks are not available due to transmission errors, it will not be possible to resolve the merge index any more.

A key application of the block merging concept in HEVC is the combination with skip mode. In previous video coding standards, skip mode was used to indicate such blocks: the motion data is speculated rather than explicitly signaled and the prediction residual is zero, i.e. no transform coefficients are sent. In HEVC, skip _ flag is signaled at the beginning of each CU in an inter-picture prediction slice, which means the following: a cu contains only one PU (2 nx 2N partition type); b. using merge mode to obtain motion data (merge _ flag equal to 1); c. residual data does not exist in the code stream.

A parallel merge estimation hierarchy indicating regions is introduced in HEVC, where the list of fused motion information candidates can be derived independently by checking whether a candidate block is located in the Merge Estimation Region (MER). Candidate blocks in the same MER are not included in the fused motion information candidate list. Thus, its motion data need not be available at list building time. When this level is, for example, 32, then all prediction units in the 32 × 32 region may build the fused motion information candidate list in parallel, since all the fused motion information candidate lists that are in the same 32 × 32MER are not inserted into the list. As shown in fig. 5, there are CTU partitions with seven CUs and ten PUs. All of the potential fused motion information candidate lists for the first PU0 are available because they are outside the first 32 x 32 MER. For the second MER, the fused motion information candidate list of PUs 2-6 cannot contain motion data from these PUs when the merge estimate within the MER should be independent. Thus, for example, when viewing PU5, no fused motion information candidate list is available and therefore is not inserted in the fused motion information candidate list. In this case, the merge list of PU5 consists of only temporal candidate motion information (if available) and zero MV candidates. To enable the encoder to trade-off parallelism and coding efficiency, the parallel merge estimation level is adaptive and signaled in the picture parameter set as log2_ parallel _ merge _ level _ minus 2.

If the current block is in Inter MVP mode, also called AMVP, the detailed process of generating the candidate motion vector prediction list is as follows.

The initial design of AMVP mode contains five MVPs from three different classes of predictors: three motion vectors from spatial neighbors, the median of the three spatial predictors, and a scaled motion vector from the co-located temporal neighboring block. Furthermore, the prediction value list is modified by reordering to place the most likely motion prediction value in the first position and by removing redundant candidates to ensure minimal signaling overhead. The original AMVP then undergoes a number of simplifications, such as removing the median predictor, reducing the number of candidates in the list from five to two, fixing the order of candidates in the list, and reducing the number of redundancy checks. The final design of the AMVP candidate list construction contains the following two MVP candidates: a. at most two spatial candidate MVPs obtained from five spatial neighboring blocks; b. a temporal candidate MVP derived from two temporal co-located blocks when two spatial candidate MVPs are not available or they are the same; c. zero motion vectors when spatial candidate motion information, temporal candidate motion information, or both are not available. As already mentioned, two spatial MVP candidates a and B are derived from five spatial neighboring blocks, as shown in the right part of fig. 6. For AMVP and inter-prediction block merging, the positions of the spatial candidate blocks are the same. The flow of the process of obtaining the two spatial candidate motion information a and B is depicted in fig. 10. For candidate a, the motion data from the two blocks a0 and a1 from the lower left corner are considered in a two-pass approach. In the first pass, it is checked whether any candidate block contains a reference index equal to the reference index of the current block. The first motion vector found will be candidate a. When all reference indices from a0 and a1 point to a reference picture different from the reference index of the current block, the related motion vector cannot be used as it is. Thus, in the second pass, the motion vector needs to be scaled according to the temporal distance between the candidate reference picture and the current reference picture. Equation (1.1) shows how the candidate motion vector mvcand is scaled according to the scaling factor. The ScaleFactor is calculated based on the temporal distance between the current picture and the reference picture of the candidate block td and the temporal distance between the current picture and the reference picture of the current block tb. The temporal distance is expressed as a difference between Picture Order Count (POC) values defining a picture display order. The scaling operation is basically the same as the scheme used for time-pass mode in h.264/AVC. This decomposition allows the ScaleFactor to be pre-computed at the slice level, since it depends only on the reference picture list structure signaled in the slice header. It should be noted that MV scaling is only performed when both the current reference picture and the candidate reference picture are short-term reference pictures. The parameter td is defined as the POC difference between the co-located picture of the co-located candidate block and the reference picture.

mv＝sign(mvcand·ScaleFactor)·((|mvcand·ScaleFactor|+27)>>8) (1.1)

ScaleFactor＝clip(-212,212-1,(tb·tx+25)>>6) (1.2)

For candidate B, candidates B0 through B2 are checked in sequence in the same manner as A0 and A1 are checked in the first pass. However, the second pass is only performed when blocks a0 and a1 do not contain any motion information, i.e., are not available or are encoded using intra-picture prediction. Next, if candidate A is found, then candidate A is set equal to candidate B, which is not scaled, and candidate B is set equal to a second, unscaled or scaled variant of candidate B. The second search pass finds the unscaled and scaled MVs from candidates B0 through B2. In general, this design allows processing a0 and a1 independently of B0, B1, and B2. B's derivation should only understand the availability of both a0 and a1 in order to search for scaled or otherwise unscaled MVs derived from B0 to B2. This dependency is acceptable in view of the fact that it significantly reduces the complex motion vector scaling operation of candidate B. Reducing the number of motion vector scalings represents a significant complexity reduction in the motion vector predictor derivation process.

In HEVC, the bottom right and center blocks of the current block have been determined to be best suited to provide a good Temporal Motion Vector Predictor (TMVP). These candidates are shown in the left part of fig. 3, where C0 represents the lower right neighbor and C1 represents the center block. Here again, the motion data of C0 is considered first and if not available, the temporal MVP candidate C is derived using the motion data from the co-located candidate block at the center. The motion data of C0 is also considered unavailable when the associated PU belongs to a CTU other than the current CTU row. This minimizes the memory bandwidth requirements for storing the co-located motion data. In contrast to spatial MVP candidates where motion vectors may refer to the same reference picture, motion vector scaling is mandatory for TMVP. Therefore, the same scaling operation as the spatial MVP is used.

Although the temporal pass-through mode in h.264/AVC always refers to the second reference picture list, i.e. the first reference picture in list 1, and is only allowed in bi-predictive slices, HEVC provides the possibility to indicate for each picture which reference picture is considered as a co-located picture. This is done by signaling the co-located reference picture list and reference picture index in the slice header and requiring that these syntax elements in all slices in the picture should specify the same reference picture.

Since the temporal MVP candidate introduces additional dependencies, its use may need to be disabled for error robustness reasons. In h.264/AVC, it is possible to disable the temporal pass-through mode (direct _ spatial _ mv _ pred _ flag) of bi-directional predicted slices in the slice header. The HEVC syntax extends this signaling by allowing TMVP (sps/slice temporal mvp enabled flag) to be disabled at the sequence level or at the picture level. Although the flag is signaled in the slice header, its value should be the same for all slices in a picture, which is a requirement for codestream consistency. Signaling the picture-level flag in the PPS will introduce a resolution dependency between SPS and PPS, since the signaling of the picture-level flag depends on the SPS flag. Another advantage of such header signaling is that if one wants to change only the value of this flag in the PPS and not other parameters, there is no need to send a second PPS.

In general, motion data signaling in HEVC is similar to that in h.264/AVC. The inter-picture prediction syntax element inter _ pred _ idc signals whether to use the reference list 0, 1, or both. For each MCP obtained from one reference picture list, the corresponding reference picture (Δ t) is signaled by the index ref _ idx _ l0/1 of the reference picture list, and MV (Δ x, Δ y) is signaled by the index MVP _ l0/1_ flag of MVP and its MVD. The flag MVD _ l1_ zero _ flag newly introduced in the slice header indicates whether the MVD of the second reference picture list is equal to zero and thus is not signaled in the bitstream. When the motion vector is fully reconstructed, the final clipping operation ensures that the value of each component of the final motion vector will always be in the range-215 to 215-1, inclusive.

If the historical candidate motion information in the historical candidate motion information list is added to the current candidate motion information list, the method in the jfet-K0104 proposal may be adopted, or other methods may be adopted to add the historical candidate motion information in the historical candidate motion information list to the fusion motion information candidate list, which is not limited in the present invention.

(3) Acquiring motion information of a current block;

the motion information of the current block can be obtained from the current candidate motion information list (including the motion information candidate list of the current block and the historical candidate motion information list) of the current block according to the existing method through the method.

More specifically, the decoding side: and if the current block is in merge/skip mode, determining the motion information of the current block according to the fusion index carried in the code stream. And if the current block is in an Inter MVP mode, determining the motion information of the current block according to the Inter-frame prediction direction, the reference frame index, the motion vector predicted value index and the motion vector residual value transmitted in the code stream.

(4) Obtaining an inter-frame prediction image of the current block according to the motion information;

more specifically, the decoding side: performing motion compensation (motion compensation) according to the motion information to obtain a predicted image; further, the step (4) may further include obtaining a residual image of the current block, and adding the inter-prediction image to the residual image to obtain a reconstructed image of the current block; and if the current block has no residual error, the predicted image is a reconstructed image of the current block.

Optionally, the third embodiment may further include updating the historical candidate motion information list using the motion information of the current block, where the step may be before step (4), after step (2), or after step (4);

specifically, the historical candidate motion information list may be updated according to the method in the jfet-K0104 proposal, or by other methods. In the proposal of jfet-K0104, the motion information of the current block is compared with the historical motion information candidates in the historical motion information candidate list, starting from the head of the historical motion information candidate list; if a certain historical candidate motion information is the same as the current block motion information, the historical candidate motion information is removed from the historical candidate motion information list. Then, the size of the historical candidate motion information list is checked, if the size of the historical candidate motion information list exceeds the preset size, the historical candidate motion information at the head of the historical candidate motion information list in the list is removed, the residual historical candidate motion information in the current candidate motion information list is shifted to the head of the historical candidate motion information list, and the motion information of the current block is added to the tail of the historical candidate motion information list. It should be noted that, in the present invention, the step of determining whether the current block motion information is the same as a certain historical candidate motion information in the historical candidate motion information list may not be performed, that is, two identical motion information may exist in the historical candidate motion information list, or two pieces of motion information may be the same after a certain processing, for example, the results of right shifting two motion vectors by 2 bits are the same.

It should be noted that, if the third embodiment does not include updating the historical candidate motion information list using the motion information of the current block, it means that the coding block in the current coding tree unit can perform inter-frame prediction using the same historical candidate motion information list, thereby allowing parallel operations to be implemented in the processing of the coding block in the coding tree unit.

In summary, the first to third embodiments are more beneficial to the parallel of the row-level and CTU-level codecs without increasing additional storage areas and having a considerable coding efficiency, and can effectively reduce the codec time. Fig. 12 is a flowchart of example operations performed by video decoder 30 shown in fig. 1 to implement an embodiment of the present invention for image decoding by applying the inter prediction method of fig. 11. One or more functional units of video decoder 30, including prediction processing unit 360, may be used to perform the method of fig. 12. In the example of fig. 12, the decoding of the picture is performed based on the inter prediction method in the method of fig. 11, and the decoding method 1200 specifically includes:

s1201 initializes a history candidate motion information list corresponding to the current coding tree unit;

s1203, adding motion information at L positions in an adjacent airspace block of the current coding tree unit to the historical candidate motion information list according to a preset sequence, wherein M is more than or equal to L and is less than or equal to N, and the L positions in the adjacent airspace block are obtained according to a preset rule;

generating a current candidate motion information list of the current coding unit or the current coding tree unit when an inter prediction type of the current coding unit or the current coding tree unit is an AMVP mode or a merge/skip mode; wherein the current candidate motion information list in the AMVP mode includes a motion vector, and in the merge/skip mode, the current candidate motion information list includes a bidirectional reference S or a unidirectional reference indication, a reference frame index, and a motion vector corresponding to a reference direction;

s1205 constructs the current candidate motion information list of the current coding tree unit or the current coding unit;

s1207, obtaining motion information of the current coding tree unit or the current coding unit from a combination of the historical candidate motion information list and the current candidate motion information list, and performing inter-frame prediction on the current coding tree unit or the current coding unit according to the motion information of the current coding tree unit or the current coding unit to obtain an inter-frame prediction image;

analyzing a code stream, wherein the current coding tree unit or a motion information index corresponding to the current coding unit acquires motion information of the current coding tree unit or the current coding unit according to the combination of the historical candidate motion information list and the current candidate motion information list, and performs inter-frame prediction on the current coding tree unit or the current coding unit according to the motion information to acquire an inter-frame prediction image;

s1209 adds the obtained inter-prediction image to the current coding tree unit or the residual image of the current coding unit, to obtain a reconstructed image of the current coding tree unit or the current coding unit.

Compared with the prior art, the decoding method adopts the updating of the historical candidate motion information list at the CTU level, allows the encoding and decoding of the row level and the CTU level to be parallel, and can effectively reduce the decoding time.

Fig. 13 is a flowchart of example operations of image encoding by implementing the fusion candidate list construction method of fig. 11 in an embodiment of the present invention according to video encoder 20 shown in fig. 1. One or more functional units of video encoder 20, including prediction processing unit 260, may be used to perform the method of fig. 13. In the example of fig. 13, the encoding of the picture is performed based on the inter-prediction method in the method of fig. 11, and the encoding method 1300 specifically includes:

s1301, initializing a historical candidate motion information list corresponding to the current coding tree unit;

s1303, adding motion information at L positions in an adjacent space domain block of the current coding tree unit to the historical candidate motion information list according to a preset sequence, wherein M is more than or equal to L which is more than or equal to N, and the L positions in the adjacent space domain block are obtained according to a preset rule;

generating a current candidate motion information list of the current coding unit or the current coding tree unit when an inter prediction type of the current coding unit or the current coding tree unit is an AMVP mode or a merge/skip mode; wherein the current candidate motion information list in the AMVP mode includes a motion vector, and in the merge/skip mode, the current candidate motion information list includes a bidirectional reference or unidirectional reference indication, a reference frame index, and a motion vector corresponding to a reference direction;

s1305 constructing a current candidate motion information list of the current coding tree unit or the current coding unit;

s1307 obtains motion information of the current coding tree unit or the current coding unit and a motion information index of the motion information from a combination of the historical candidate motion information list and the current candidate motion information list;

s1309 performs inter-frame prediction on the current coding tree unit or the current coding unit according to the motion information of the current coding tree unit or the current coding unit to obtain an inter-frame prediction image;

s1311, subtracting the obtained inter-prediction image from the current coding tree unit or an original image of the current coding unit to obtain a residual image;

s1213, the residual image and the motion information index are encoded to form a code stream.

Compared with the prior art, the decoding method adopts the updating of the historical candidate motion information list at the CTU level, allows the encoding and decoding of the line level and the CTU level to be parallel, and can effectively reduce the encoding time.

Fig. 14 shows an inter-frame prediction apparatus 1400 according to the present invention, which has a function of implementing the inter-frame prediction method shown in fig. 11, and includes: an initialization module 1401, configured to initialize a historical candidate motion information list corresponding to a current coding tree unit, where the historical candidate motion information list includes N storage spaces, the N storage spaces are used to store historical candidate motion information, the initialized historical candidate motion information list includes at least M empty storage spaces, M is less than or equal to N, M and N are integers, the current coding tree unit is included in a coding tree unit set (Slice) formed by multiple coding tree units, and the current coding tree unit is not a first coding tree unit in the coding tree unit set according to a predetermined processing order; a historical candidate motion information list building module 1403, configured to add, to the historical candidate motion information list, motion information at L positions in a spatial neighboring block of the current coding tree unit according to a predetermined order, where M is greater than or equal to L is greater than or equal to N positions in the spatial neighboring block, and the positions are obtained according to a preset rule; a current candidate motion information list constructing module 1405, configured to construct a current candidate motion information list of the current coding tree unit or a current candidate motion information list of a current coding unit, wherein the coding unit is divided by the coding tree unit; and a prediction module 1407 configured to perform inter prediction on the current coding tree unit or the current coding unit according to a combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit.

Optionally, the initializing the historical candidate motion information list corresponding to the current coding tree unit includes clearing the historical candidate motion information list such that M equals N. Optionally, the M positions in the adjacent airspace blocks are that a first candidate motion information is obtained from a preset position in the adjacent airspace block, the position where the first candidate motion information is obtained is taken as a starting point, and the remaining M-1 candidate motion information is obtained at intervals of a preset step length, where the preset step length is a fixed value, or the preset step length is changed according to a preset rule.

Optionally, the prediction module 1405 is configured to: acquiring motion information of the current coding unit according to a combination of a current candidate motion information list and the historical candidate motion information list of the current coding unit, and performing inter-frame prediction on the current coding unit according to the acquired motion information; the apparatus 1400 further comprises: a historical motion information list update module 1407 for updating the historical candidate motion information list based on the current coding unit motion information.

Optionally, the historical motion information list updating module updates the historical candidate motion information list according to the following rule: if the M positions are not filled, adding the motion information of the current coding unit as historical motion information into an empty storage space which is closest to the N-M position in the M positions in the historical candidate motion information list; or; if the M positions are filled, removing the historical motion information which is added into the historical candidate motion information list at the earliest according to a first-in first-out principle, shifting the residual historical motion information to the removed historical motion information position, and adding the current coding unit motion information serving as the historical motion information into the tail part of the historical candidate motion information list, wherein one end of the historical candidate motion information list, which contains the latest added historical motion information, is the tail part of the historical candidate motion information list.

Optionally, the current candidate motion information list building block 1403 is further configured to; adding the historical candidate motion information in the historical candidate motion information list into the current candidate motion information list of the current coding unit; correspondingly, the prediction module 1405 acquires the motion information of the current coding unit according to the current candidate motion information list of the current coding unit, and performs inter prediction on the current coding unit according to the acquired motion information.

Optionally, the prediction module 1405 is configured to obtain motion information of the current coding unit according to a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit, and perform inter-frame prediction on the current coding unit according to the obtained motion information; the prediction module 1405 is further configured to inter-predict another coding unit based on the same method as the current coding unit, where the another coding unit is located after the current coding unit in a preset processing order and belongs to the coding tree unit as the current coding unit, and a historical motion information list used in inter-prediction of the another coding unit includes historical motion information in a historical motion information list used in inter-prediction of the current coding unit.

Optionally, the historical candidate motion information list building module 1403 is configured to, according to a clockwise order, add motion information at L positions in the spatial neighboring block to the historical candidate motion information list by using the spatial neighboring block at the lower left corner of the current coding tree unit as a starting point and the spatial neighboring block at the upper right corner of the current coding tree unit as an end point.

Fig. 15 shows an encoding apparatus 1500 according to the present invention, which has a function of implementing the encoding method shown in fig. 12, and includes: inter prediction means 1501 (the same as the inter prediction means 1400) for acquiring an inter prediction image of the current coding tree unit or an inter prediction image of the current coding unit; the acquiring of the inter-prediction image of the current coding tree unit or the inter-prediction image of the current coding unit includes: acquiring motion information of the current coding tree unit or the current coding unit and a motion information index of the motion information from a combination of the historical candidate motion information list and the current candidate motion information list; according to the motion information of the current coding tree unit or the current coding unit, performing inter-frame prediction on the current coding tree unit or the current coding unit to obtain an inter-frame prediction image; a residual calculation module 1503, configured to subtract the current coding tree unit or the original image of the current coding unit from the obtained inter-frame predicted image to obtain a residual image; and an encoding module 1505 for encoding the residual image and the motion information index to form a code stream.

Fig. 16 shows a decoding apparatus 1600 according to the present invention, which has a function of implementing the decoding method shown in fig. 13, and includes: inter prediction means 1601 (same as the inter prediction means 1400) for acquiring an inter prediction image of the current coding tree unit or an inter prediction image of the current coding unit; and a reconstruction module (1603) for adding the obtained inter-prediction image to the current coding tree unit or a residual image of the current coding unit to obtain a reconstructed image of the current coding tree unit or the current coding unit.

Fig. 17 is a general schematic diagram of an apparatus for implementing the methods of fig. 11 to 13, where the apparatus 1700 may be an inter-frame prediction apparatus, an encoding apparatus, and a decoding apparatus, the apparatus including an inter-frame prediction apparatus including a digital processor 1701 and a memory 1702 in which an executable instruction set is stored, the digital processor reading the instruction set stored in the memory for implementing the methods described in fig. 11 to 13.

In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer readable media may comprise computer readable storage media corresponding to tangible media, such as data storage media or communication media, including any medium that facilitates transfer of a computer program from one place to another, such as according to a communication protocol. In this manner, the computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium, or (2) a communication medium, e.g., a signal or carrier wave. A data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementing the techniques described in this disclosure. The computer program product may include a computer-readable medium.

By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that the computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory tangible storage media. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The instructions may be executed by one or more processors, such as one or more Digital Signal Processors (DSPs), general purpose microprocessors, Application Specific Integrated Circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, the term "processor," as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules for encoding and decoding, or incorporated in a composite codec. Also, the techniques may be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a variety of devices or apparatuses including a wireless handset, an Integrated Circuit (IC), or a collection of ICs (e.g., a chipset). This disclosure describes various components, modules, or units to emphasize functional aspects of the apparatus for performing the disclosed techniques, but does not necessarily require realization by different hardware units. Specifically, as described above, the various units may be combined in a codec hardware unit, or provided by a collection of interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware.

Claims

1. An inter prediction method, comprising:

initializing a historical candidate motion information list corresponding to a current coding tree unit, wherein the historical candidate motion information list comprises N storage spaces, the N storage spaces are used for storing historical candidate motion information, the initialized historical candidate motion information list comprises at least M vacant storage spaces, M is less than or equal to N, M and N are integers, the current coding tree unit is contained in a coding tree unit set (Slice) formed by a plurality of coding tree units, and the current coding tree unit is not the first one in a preset processing sequence in the coding tree unit set;

adding the motion information of L positions in a spatial adjacent block of the current coding tree unit to the historical candidate motion information list according to a preset sequence, wherein M is more than or equal to L and is less than or equal to N positions in the spatial adjacent block are obtained according to a preset rule;

constructing a current candidate motion information list of the current coding tree unit or a current candidate motion information list of the current coding unit, wherein the coding unit is obtained by dividing the coding tree unit; and

and performing inter-frame prediction on the current coding tree unit or the current coding unit according to the combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or the combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit.

2. The method of claim 1, wherein: the initializing the historical candidate motion information list corresponding to the current coding tree unit includes clearing the historical candidate motion information list such that M is N.

3. The method of claim 1, wherein: the M positions in the adjacent airspace blocks are used for acquiring first candidate motion information from a preset position in the adjacent airspace blocks, and acquiring the rest M-1 candidate motion information by taking a preset step length as an interval by taking the position for acquiring the first candidate motion information as a starting point.

4. The method of claim 3, wherein: the preset step length is a fixed value, or the preset step length is changed according to a preset rule.

5. The method of any one of claims 1-4, wherein: the inter-prediction of the current coding tree unit or the current coding unit according to a combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit includes:

acquiring motion information of the current coding unit according to a combination of a current candidate motion information list and the historical candidate motion information list of the current coding unit, and performing inter-frame prediction on the current coding unit according to the acquired motion information; and

the method further comprises the following steps:

updating the historical candidate motion information list based on the current coding unit motion information.

6. The method of claim 5, wherein: said updating the historical candidate motion information list based on the current coding unit motion information comprises:

if the M positions are not filled, adding the motion information of the current coding unit as historical motion information into an empty storage space which is closest to the N-M position in the M positions in the historical candidate motion information list; or;

if the M positions are filled, removing the historical motion information which is added into the historical candidate motion information list at the earliest according to a first-in first-out principle, shifting the residual historical motion information to the removed historical motion information position, and adding the current coding unit motion information serving as the historical motion information into the tail part of the historical candidate motion information list, wherein one end of the historical candidate motion information list, which contains the latest added historical motion information, is the tail part of the historical candidate motion information list.

7. The method of claim 5, wherein before obtaining the motion information of the current coding unit from a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit and inter-predicting the current coding unit according to the obtained motion information, the method further comprises;

adding the historical candidate motion information in the historical candidate motion information list into the current candidate motion information list of the current coding unit;

the acquiring motion information of the current coding unit according to a combination of the current candidate motion information list and the historical candidate information motion list of the current coding unit, and inter-predicting the current coding unit according to the acquired motion information includes:

and acquiring the motion information of the current coding unit according to the current candidate motion information list of the current coding unit, and performing inter-frame prediction on the current coding unit according to the acquired motion information.

8. A method according to any one of claims 1 to 3, characterized by: the inter-prediction of the current coding tree unit or the current coding unit according to a combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit includes: acquiring motion information of the current coding unit according to a combination of a current candidate motion information list and the historical candidate motion information list of the current coding unit, and performing inter-frame prediction on the current coding unit according to the acquired motion information; and

the method further comprises the following steps:

and performing inter prediction on another coding unit based on the same method as the current coding unit, wherein the another coding unit is positioned after the current coding unit according to a preset processing order and belongs to the coding tree unit with the current coding unit, and a historical motion information list adopted by the inter prediction of the another coding unit comprises historical motion information in the historical motion information list adopted by the inter prediction of the current coding unit.

9. The method of any one of claims 1-7, wherein: adding the motion information at L positions in the spatial neighboring blocks of the current coding tree unit to the historical candidate motion information list according to a predetermined order, comprising:

and according to a clockwise sequence, taking the spatial adjacent block at the lower left corner of the current coding tree unit as a starting point, taking the spatial adjacent block at the upper right corner of the current coding tree unit as an end point, and adding the motion information at L positions in the spatial adjacent blocks into the historical candidate motion information list.

10. An inter-frame prediction apparatus, comprising:

an initialization module, configured to initialize a historical candidate motion information list corresponding to a current coding tree unit, where the historical candidate motion information list includes N storage spaces, the N storage spaces are used to store historical candidate motion information, the initialized historical candidate motion information list includes at least M empty storage spaces, M is less than or equal to N, M and N are integers, the current coding tree unit is included in a coding tree unit set (Slice) composed of multiple coding tree units, and the current coding tree unit is not a first coding tree unit in the coding tree unit set according to a predetermined processing order;

a historical candidate motion information list construction module, configured to add, according to a predetermined order, motion information at L positions in a spatial neighboring block of the current coding tree unit to the historical candidate motion information list, where M is greater than or equal to L is greater than or equal to N positions in the spatial neighboring block and is obtained according to a preset rule;

a current candidate motion information list construction module, configured to construct a current candidate motion information list of the current coding tree unit or a current candidate motion information list of a current coding unit, where the coding unit is obtained by dividing the coding tree unit; and

a prediction module, configured to perform inter prediction on the current coding tree unit or the current coding unit according to a combination of the current candidate motion information list and the historical candidate motion information list of the current coding tree unit or a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit.

11. The apparatus of claim 10, wherein: the initializing the historical candidate motion information list corresponding to the current coding tree unit includes clearing the historical candidate motion information list such that M is N.

12. The apparatus of claim 10, wherein: the M positions in the adjacent airspace blocks are used for acquiring first candidate motion information from a preset position in the adjacent airspace blocks, and acquiring the rest M-1 candidate motion information by taking a preset step length as an interval by taking the position for acquiring the first candidate motion information as a starting point.

13. The apparatus of claim 12, wherein: the preset step length is a fixed value, or the preset step length is changed according to a preset rule.

14. The apparatus of any one of claims 10-13, wherein: the prediction module is to: acquiring motion information of the current coding unit according to a combination of a current candidate motion information list and the historical candidate motion information list of the current coding unit, and performing inter-frame prediction on the current coding unit according to the acquired motion information; the device further comprises:

a historical motion information list update module to update the historical candidate motion information list based on the current coding unit motion information.

15. The apparatus of claim 14, wherein: the historical motion information list updating module updates the historical candidate motion information list according to the following rules:

16. The apparatus of claim 15, wherein the current candidate motion information list construction module is further configured to;

the prediction module is configured to obtain motion information of the current coding unit according to the current candidate motion information list of the current coding unit, and perform inter-frame prediction on the current coding unit according to the obtained motion information.

17. The apparatus of any one of claims 10 to 13, wherein: the prediction module is configured to obtain motion information of the current coding unit according to a combination of the current candidate motion information list and the historical candidate motion information list of the current coding unit, and perform inter-frame prediction on the current coding unit according to the obtained motion information;

the prediction module is further configured to perform inter prediction on another coding unit based on the same method as the current coding unit, where the another coding unit is located after the current coding unit according to a preset processing order and belongs to the coding tree unit as the current coding unit, and a historical motion information list adopted by the inter prediction of the another coding unit includes historical motion information in a historical motion information list adopted by the inter prediction of the current coding unit.

18. The apparatus of any one of claims 10-17, wherein: the historical candidate motion information list construction module is configured to, according to a clockwise order, add motion information at L positions in the spatial neighboring block to the historical candidate motion information list, with the spatial neighboring block at the lower left corner of the current coding tree unit as a starting point and the spatial neighboring block at the upper right corner of the current coding tree unit as an end point.

19. An encoding method, characterized in that an inter-predicted image of a current coding tree unit or an inter-predicted image of a current coding unit is obtained according to the method of any one of the preceding claims 1 to 9; wherein the obtaining of the inter-predicted image of the current coding tree unit or the inter-predicted image of the current coding unit according to the method of any one of claims 1 to 9 comprises: acquiring motion information of the current coding tree unit or the current coding unit and a motion information index of the motion information from a combination of the historical candidate motion information list and the current candidate motion information list; according to the motion information of the current coding tree unit or the current coding unit, performing inter-frame prediction on the current coding tree unit or the current coding unit to obtain an inter-frame prediction image;

subtracting the obtained inter-prediction image from the original image of the current coding unit or the current coding unit to obtain a residual image;

and coding the residual image and the motion information index to form a code stream.

20. A decoding method, characterized in that an inter-predicted image of a current coding tree unit or an inter-predicted image of a current coding unit is obtained according to the method of any one of the preceding claims 1 to 9;

and adding the obtained inter-frame prediction image with the current coding tree unit or the residual image of the current coding unit to obtain a reconstructed image of the current coding tree unit or the current coding unit.

21. An encoding apparatus, comprising the inter prediction apparatus according to any one of claims 10 to 18, for obtaining an inter prediction image of a current coding tree unit or an inter prediction image of a current coding unit; the acquiring of the inter-prediction image of the current coding tree unit or the inter-prediction image of the current coding unit includes: acquiring motion information of the current coding tree unit or the current coding unit and a motion information index of the motion information from a combination of the historical candidate motion information list and the current candidate motion information list; according to the motion information of the current coding tree unit or the current coding unit, performing inter-frame prediction on the current coding tree unit or the current coding unit to obtain an inter-frame prediction image;

a residual calculation module, configured to subtract the original image of the current coding tree unit or the current coding unit from the obtained inter-frame predicted image to obtain a residual image;

and the coding module is used for coding the residual image and the motion information index to form a code stream.

22. A decoding apparatus, comprising the inter prediction apparatus of any one of claims 10 to 18, for obtaining an inter prediction image of a current coding tree unit or an inter prediction image of a current coding unit; and the number of the first and second groups,

a reconstruction module, configured to add the obtained inter-prediction image to the current coding tree unit or a residual image of the current coding unit to obtain a reconstructed image of the current coding tree unit or the current coding unit.

23. An inter-prediction apparatus comprising a digital processor and a memory having stored therein an executable instruction set, the digital processor reading the instruction set stored in the memory for implementing the inter-prediction method as described in any one of claims 1 to 9.

24. An encoding apparatus comprising a digital processor and a memory having stored therein a set of executable instructions, the digital processor reading the set of instructions stored in the memory for implementing a decoding method as described in claim 19.

25. A decoding apparatus comprising a digital processor and a memory having stored therein a set of executable instructions, the digital processor reading the set of instructions stored in the memory for implementing an encoding method as described in claim 20.